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Greetings, and thanks for the great web forum you all have here; I've been lurking here for a long time, as I've used this forum as my primary research tool as I've worked on my 07 Cayman S (which I bought last June). In the past, I've owned 2 944s and a 944 Turbo, which was heavily modified.

As I mentioned, I did a lot of research on this forum; after this research I decided to install the IPD Plenum & 997 GT3 throttle body upgrade on my 07 Cayman S. Since there seems to be a lot of discussion about this modification, I thought I'd share my impressions.

First off, let me say that YES, the Cayman S's performance in stock form is impressive, and the Porsche engineers obviously know what they're doing in terms of building a great car. I also acknowledge that the single best improvement that one can make to the performance of a Porsche road car is to improve the driver's ability. That being said, one of the reasons I enjoy owning sports cars is because I like to tinker and personalize in order to have an ongoing project. I also recognize that there is a widespread belief that Porsche "throttled back" the performance of the Cayman S so that it would not threaten the 911 Carrera's sales (a stance that Porsche seems to be softening about lately, considering that they are increasingly moving the 911 into the "luxury GT" class to compete against Aston and Maserati, and the Cayman is increasingly becoming the company's go-to performance machine).

I did roughly a year's worth of research before doing any modifications to my Cayman S. According to what I've found, the most worthwhile engine upgrades to a 987 Cayman S are (in order of claimed impact):

Exhaust ($1600+)
ECU Reflash ($1000)
IPD Plenum & GT3 Throttle Body ($1100)
Evolution Motorsports Intake ($300)
De-Snorked Intake Vent ($0)

I put the exhaust upgrade at #1 because it is claimed that it noticeably improves the performance AS WELL AS the sound of the car, which is definitely a big part of the subjective experience. The ECU reflash might actually have the most noticeable impact to performance, but it should also come AFTER all the other modifications in order to maximize their impact.

When I was trying to decide what to do first, I actually went with the de-snork first because, well, it didn't cost anything. I didn't notice any performance gain from removing the restrictor plate on the driver's side intake, but it's been said that improving airflow in this way pays off LATER (ie when you do the reflash).

My first REAL modification was to purchase the IPD Plenum and GT3 Throttle Body. This took a lot of deliberation after a lot of research.

First, let me explain the theory behind this upgrade (in case anyone here is new to this modification). The 987 Cayman S comes stock with a 3.4-liter boxer flat-six that is essentially the same as the 3.4 that came with the 996 Carrera (the Cayman's motor is based on the Boxster's, but there are more shared components than not). If one looks at the intake plenum hoses (which are the same diameter as those on the Carrera) and follow the hose that leads to the throttle body, one can easily see that the diameter of the TB is narrower than that of the intake plenum. The conclusion that many people reach about this is that Porsche "throttled-back" the Cayman by installing a smaller-than-optimum throttle body (74mm) even though the intake diameter is the same as the Carrera. To remedy this, the company IPD built an intake plenum that optimizes airflow but also mates up to a 997 GT3 throttle body (82mm). The Porsche ECU would, in theory, sense the increase in airflow and match that with an increase in fuel, which would result with an increase in power. In theory.

There is a lot of controversy about this product, considering that some dyno runs show noticeable gains and some show no gains at all. Many have concluded that the Porsche ECU can't be outsmarted with a bolt-on mod, and that it doesn't matter whether or not one improves the POTENTIAL for increased airflow because the ECU will only let so much air in at a time; the only way to truly make the most of this mod would be to reflash the ECU after installing the plenum/TB. After doing the reflash, people notice significant power gains from this combination.

On Planet9's boards, one user did extensive testing with a 981-model Cayman S and came to the conclusion that the Porsche ECU actually CLOSES the throttle body slightly at WOT with the plenum/GT3TB installed, because the ECU is programmed to only let a certain amount of air & fuel into the chamber at WOT (again, to limit the Cayman's performance vs. the 911?). This would explain why the plenum/TB upgrade shows negligible peak HP gains. The same user (sorry, it was so long ago that I don't remember his name and don't have the thread handy) found that the combination of reflashing AND the plenum/TB upgrade showed SIGNIFICANT power gains over 1) stock, 2) just reflashing, or 3) just the plenum/TB upgrade. His conclusion: the plenum/TB upgrade IS worth it... as long as you are planning on doing the ECU reflash.

Well, I have done the plenum/TB upgrade, but have NOT reflashed YET. I plan on doing exhaust next (probably next summer) and the reflash after that. I planned from the beginning to do these upgrades one step at a time in order to see their individual impact as well as cumulative impact.

Here's what I can report about the plenum/TB upgrade: it might not show peak HP gains on a dyno, but I can report that I notice instant and very obvious improvements in throttle response and low-end torque. This makes sense to me: although the Porsche ECU is programmed to limit the airflow at WOT in order to limit peak HP, it has no reason to limit the airflow at lower RPMs, because that level of power would have been achieved higher in the rev range. In stock form, the 3.4 flat six has a fairly "peaky" power-band, with a VTEC-like surge occurring at about 5500rpm and on to redline; what the plenum/TB upgrade did was make that power band a bit smoother, with a noticeable improvement in "pull" from 2000-4000rpm. This makes "around-town" and low-rev-range driving much more pleasurable, in my opinion. Moreover, that aforementioned VTEC-like surge now occurs lower in the rev range (somewhere between 4500 and 5000). For that matter, the engine sound is somewhat meaner and more raw, especially above 5000rpm. You also get a cool "cold-air intake" sound at low revs, which some can either take or leave.

Is peak HP increased? Maybe not, but the powerband as a whole certainly FEELS as though it is, and the car almost definitely accelerates more quickly in real-world situations. Would perfectly-executed 0-60 sprints be improved by this upgrade? Maybe not, because in order to get a perfect 0-60 launch, one has to hold the throttle at 4500rpm and dump the clutch (according to Road & Track); as reported elsewhere, the Porsche ECU limits the air-fuel mixture at WOT. But does the upgrade improve the "fun" factor in real-world situations? Absolutely. Noticeably. Without question.

So. Is it worth it? To me? Yes. For everyone? Tough to say. At over $1000, it isn't cheap, and it's tough to say what sort of value to place on a mod that probably doesn't improve peak HP or the maximum potential of the car's acceleration. According to authorities, it IS worth it, as long as you're planning on reflashing the ECU (especially if you're also planning on upgrading the exhaust). Personally, I'm glad I did it: as far as I'm concerned, it made an already fun and fast car more fun and faster (although I can't prove it with dyno numbers); it improved the engine sound (in my opinion), and dressed up the engine bay a bit.

I give "thumbs-up" to the IPD plenum & 997 GT3 throttle body upgrade. I also plan on doing exhaust and a reflash, so I will keep you all posted on the improvements as I do them!

I hope this was helpful to someone out there! Again, thanks for the all the great info on these boards.
 

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Thanks for sharing your experiences. As I recall at one point in the past there was some debate as to whether or not the GT3 throttle body was overkill in terms of diameter and that a throttle body diameter between the GT3 and stock was more of an ideal fit. I don't ever recall if anyone ever tested all the combos, in your research did you run across that issue and was there ever any solid resolution?
 

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Thanks for the post. Very good info.

If I'm going to spend 4 large, I would really like to see improved TQ/HP and w/o a dyno baseline this type of work lends itself to the placebo effect for mods.

I expect to get a baseline for my '09 Base over the next few months and make some of the mods (exhaust, plenum and TB) and follow each with a dyno to provide real data.


Eddie
 

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My 981 2.7, I notice an improvement after BMC air filters, headers, exhaust, and IPD/TB without a tune. Seems the gains are in the higher RPM range and my perception is lower RPMs are weaker (maybe cause higher RPMs are faster). No dynos, but my test shows to 60 time is improved less than 1 sec. Its like around 5 seconds now from the claimed 5.6 critics test.

Its nothing spectacular though and I wouldn't recommend spending 4k for the minor increase. I think if 981 ECU stage 2 tune is released, I'll get more real benefits.
 

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CJFusco,

Nice to take time to offer your analysis. I appreciated the time you gave. Also agree with it. Nicely done and welcome officially to the forum. Hope to see more write-ups from you as you progress with the tinkering.
 

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Discussion Starter #6
Thank you all for the kind words. I've been lurking here for a long time, and the information here is great. I have been an active Pelican Parts member for... well, almost 15 years, I'd bet; whereas that forum is a treasure trove of information about classic 911s and the 944-series, it is far more old-Porsche centric than this site.

Thanks for sharing your experiences. As I recall at one point in the past there was some debate as to whether or not the GT3 throttle body was overkill in terms of diameter and that a throttle body diameter between the GT3 and stock was more of an ideal fit. I don't ever recall if anyone ever tested all the combos, in your research did you run across that issue and was there ever any solid resolution?
Yes, I remember coming across that theory. If I remember correctly, the consensus was that going with the IPD plenum that mates to the stock 74mm plenum is probably adequate and gives similar performance to the 82mm version IF YOU ARE NOT PLANNING ON REFLASHING THE ECU. From what I remember, the 82mm TB showed greater gains than the 74mm TB with an ECU reflash. Might a Carrera S TB be adequate and give just as good performance as the GT3 TB? Possibly... although it is interesting that the diameter of the stock plenum is the same diameter of the GT3 throttle body... what's fun about upgrades like this is that time and trial-and-error show us the best way to go. After another ten years, these mods will be tried-and-true (if they work).
 

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Discussion Starter #7
CJFusco,

Nice to take time to offer your analysis. I appreciated the time you gave. Also agree with it. Nicely done and welcome officially to the forum. Hope to see more write-ups from you as you progress with the tinkering.
GiantKiller, I like the black-and-silver motif on your Cayman; I have been thinking of going in a similar direction: I'd like to get one of the Boxster Spyder intake vent sets, which have a silver perimeter, and maybe the sliver lower arms for the mirrors as well as the silver accents on the front spoiler. The Cayman R decal is a possibility, too. Right now, my top two aesthetic mods would be the Boxster Spyder intakes and a glass engine cover... but since I'm house-hunting and getting married in two months, I gotta take one thing at a time.

Here are my current rides, as well as a set of before-and-after pics of the engine bay.

IMG_1138.JPG IMG_0628.JPG IMG_1052.JPG IMG_1338.JPG
 

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Discussion Starter #8
Also, I just realize that i posted this in the wrong forum... it was supposed to go in the modifications forum. WHOOPS! Sorry!
 

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Thanks, K-Man.

Since I'm still in the process of introducing myself, here are my previous P-cars: an 83 944 which I lightened quite a bit and did some suspension work, and a more-heavily-modified (although still "tasteful") 944 Turbo:

IMG_1140.JPG IMG_1141.JPG IMG_1142.JPG IMG_1144.JPG
 

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just subscribing. planning to go same route - just ordered second hand GT3 tb. Unsure about headers or cat back. opinions seem to be split... Nice write up dude.
 

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I have done all the above mods IPD plenum gt3 throttle body Fabspeed MaxFlo exhaust schenel long tube indy style merge collectors stainless steel catless headers wevo 95 durometer transmission mounts desnorked intake mod and I've had both open flash tablet tuning and now I'm running evolution Motorsports Rs 370 tuning. I also have the BMC Airfilter installed now but am switching to the EVOMS INTAKE filter assy. My car is now a animal! I also installed a set of Cayman GTS Alcatera sport seats and a full carbon fibre GT3 style rear wing. The seat of the pants dyno says much more hp and vastle improved acceleration.
 
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CJ, thanks for sharing this.
My understanding that things are not the same for .2 cars.
It's weird to see at Softronics' site that they omit IPD plenums for .2 cars.
As for the power band - i'm really disliking that "weak" engine feel up to 4,000-4,500 rpm, so if IPD could improve ti i would be really happy...
 

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Discussion Starter #14
UPDATE:

If there's any real irony in the world, it's that the Fabspeed Maxflo exhaust that I ordered for my Cayman S before the accident arrived at my door on the day that I found out that my car is totaled.

On the day of my brother's 30th birthday, and also my fiancee's bachelorette party (we're getting married in a month and a half), I went to do the paperwork and put a deposit down on my first house...

... and then on the way home, this happened.

IMG_1445.JPG

I was waiting to turn left into a supermarket parking lot, at a dead stop with my blinker on. Needless to say, she got a ticket. Everyone is okay, and, yes, she has insurance.

The engine did cut out when she hit me, and there was smoke at the initial impact. The engine did start afterward, and idled okay, but it sounded different; I suspect some exhaust components were damaged. Interestingly -- again, weird timing -- as I had a Fabspeed Maxflo cat-back exhaust already on the way.

Of course, this happened on the Saturday of a three-day weekend.

There was a delay in the process because the tow yard wouldn't release the car to Auto Associates without an in-person signature from yours truly. The problem with this is that as a high school teacher and fall sports head coach, my work hours are 7am until 6pm (after which I'm usually grading papers... don't listen to the FOX News pundits who tell you that teaching is a part-time job; sure, we get Summers off, which is great, but I put in at least 70 hours every week). Happily, the woman who manages the yard agreed to stay a little bit later on Wednesday night so that I could sign the release.

The estimate from my local Porsche specialty shop is that the repair would cost, using new parts, 12-15k (about 7k of which is parts). There is no mechanical damage, and the car is in much better shape than I'd first anticipated. It turns out that I was wrong about the engine compartment/floor mat issue. The engine compartment is fine. The floor pan is fine. All shut lines are as they should be: everything opens and closes with the appropriate gaps between panels, including in the rear trunk. There are some creases in the internal body work, but it's easily repairable. Moreover, that troubling-looking gap between the spoiler and the trunk lid is because the spoiler strut came loose and the spoiler itself is off-kilter. The shut-line is as it should be.

In other words, the car is repairable and should drive as it was. And yet the other party's insurance company wants to total the car. I was told that this insurance company has a tendency to be quick to total; the same Porsche shop had a very repairable GT3 RS in the shop recently, and the same insurance company wanted to junk it even though the repair bill was only a fraction of the car's value.

I'm going to speak to my insurance adjustor once business hours resume on Monday to see if totaling is really necessary. Failing that, I'm heavily leaning toward taking the payout from the total, paying off the remaining balance that I owe on the car, buying it back from the insurance company with a salvage title (I was given a ballpark figure of $8k), and repairing it "on my dime." The way CT's salvage title rebuild process works is that we would have to document every step of the repair and keep all receipts, and then submit the car to a DMV inspection -- a big pain in the ***, to be sure -- and then the title would be changed from "Salvage" to "Rebuilt". It's probably not as a good a scenario as getting the "totaled" verdict reversed, but it's better than not having a P-car at all. Moreover, it might be nice to go into my first months of home ownership without a car payment! (home inspections are on Wednesday!).

So... I might have a Fabspeed Maxflo cat-back system (with the secondary cat bypass tubes) on my car the next time I drive it... that is, if I don't break down and take the money and put it toward a classic 911 instead...

Stay tuned!
 
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