Planet-9 Porsche Forum banner
1 - 20 of 33 Posts

·
Registered
Joined
·
28 Posts
Discussion Starter · #1 ·
Hi guys, first post so far on the forums since I just got my own croc, so here goes nothing!

Have done my research around and i have managed to get loads of information from the forums with regards to Capristo headers and muffler aka the full exhaust system.

Question goes as to what's the main difference between the 4 cat version and the 2 cat version? Understand that the latter gets 2 cats only due to the rear mufflers having no cats and thus being louder, and most probably better performance gains. Is it that discernible?

And CEL of course..does the 2 differ that much with the absence/addition of the 2 cats?

Inputs would be greatly welcome here, once doubts are cleared, the exhaust would be coming in 2 weeks approx and I'm sure it's going to be a long wait!
 

·
Administrator
Joined
·
34,474 Posts
I haven't seen a dyno of the 2 cat vs. 4 cat system, but I would suspect that 4 cat system makes a little less power, based on 0 cat vs 2 cat headers it is probably something in the 5hp range, not anything you'd really be able to feel. The 4 cat system can prevent the CEL if the sensor is located aft of the 2nd cat, and of course whether you get one and how often you'd get one with a 2 cat system depends on a lot of factors like weather, driving style, gas quality, and your ECU revision.

Hope that helps.
 

·
Registered
Joined
·
1,755 Posts
It is also my opinion that if you go for the two cat system, remove the cats that are integrated into the headers. They are most restrictive. I have seen 20+ HP gains from removing these cats alone.
 

·
Administrator
Joined
·
34,474 Posts
It is also my opinion that if you go for the two cat system, remove the cats that are integrated into the headers. They are most restrictive. I have seen 20+ HP gains from removing these cats alone.
That number cannot be accurate as I have tested factory manifolds with cats vs. headers and the difference was only 6-8 HP.
 

·
Registered
Joined
·
1,755 Posts
That number cannot be accurate as I have tested factory manifolds with cats vs. headers and the difference was only 6-8 HP.
That is the problem Ken... cats. Numbers are very accurate and more and more people are repeating them. Look at the dyno forum, call Tony at EPL. Cats in headers are THE killer. This is the only mod these cars truly need.

I will be posting a DIRECT comparison in the dyno forum in the next couple hours.

Here is what adding cat less headers to a highly tuned car (borla, srp) will do:



Here is what adding flash and cat less headers will do to a stock car:



Tomasz
 

·
Administrator
Joined
·
34,474 Posts
Ok so catless headers on a tuned car in your instance made 11hp peak, that's certainly a good improvement and I'm assuming those runs were done on the same day? There have also been dyno runs where adding catless headers have LOST horsepower vs. stock manifolds with cats. How do you explain that? Dyno error? Improperly tuned catless headers? Too little backpressure?

I guess what I'm trying to say is that having cats in the headers will be restrictive to some degree, but the actual impact on the performance of the car is going to vary given a lot of conditions, such as other components the car has installed, whose catless headers they are (brand), etc. etc. Thus I would caution a blanket statement that removing cats from the headers will release 20hp.

We haven't even discuss the other point yet and that's the environmental impact of having no cats on a car vs. at least having something like 100 or 200 cel "race" cats. Some people won't be comfortable running a car with no cats whatsoever. Of course you could keep some cats in the rear portion of the exhaust near the muffler as opposed to up front near the headers.

We should also mention that different header designs emphasize different things. Some emphasize HP up high while giving up torque down low or vice-versa, so buyers need to make an educated decision about what they want out of their car and what choice is right for them.
 

·
Registered
Joined
·
1,755 Posts
I agree that different sets of headers from different manufacturers are likely to behave differently. Though, it is my belief that most of teh gain comes from removal of cats not from a great header design.

I would like to see more testing done on various headers. They are probably a better mod for many here - no drone, super easy to install, etc. Gatorbite?

Here is the link to my findings (I also address your environmental question.): http://www.planet-9.com/porsche-dyno-charts/45814-cat-less-headers-dyno-comparisons.html
 

·
Registered
Joined
·
169 Posts
Ken is basically right, but a few comments.
I'm speaking to nobody in particular here.

Ok so catless headers on a tuned car in your instance made 11hp peak, that's certainly a good improvement and I'm assuming those runs were done on the same day? There have also been dyno runs where adding catless headers have LOST horsepower vs. stock manifolds with cats. How do you explain that? Dyno error? Improperly tuned catless headers? Too little backpressure?
Runs on the same day can actually be undesireable, depending on the room conditions and setup procedures.
Climate controlled cell? Great. Open conditions? Might be worse.
SAE dyno corrections don't compensate for the map change/adaptation in the DME.
Did it get warmer/cooler? Did the pressure change? How was DME re-adaptation accomplished?
Sometimes same day results are hampered by minimal adaptation.
Tire pressure, engine parameters (oil/water temp?), tie down load etc. etc.
My point is, people don't use proper standardization techniques with their tests.
When we did SAE test runs, most of the day was spent normalizing variables to get accurate results.
I haven't seen that here, or on most forums for that matter.
Now, lol, some will use the logic "if you don't like my dyno runs, then all dyno results are flawed and unreliable"
Not so. There are standardized setup procedures that apply for both engine and chassis dyno testing.
The chassis dyno introduces more modes of variability than an engine dyno, however,
the variables can be accounted for to minimize the confidence window.
As I said in the other thread, I've seen +/- 10% on a given day by being undisciplined with contributing variables.
Think about that. You can show a gain/loss on all of these mods by allowing the variables to go the wrong way.

K-Man S said:
I guess what I'm trying to say is that having cats in the headers will be restrictive to some degree, but the actual impact on the performance of the car is going to vary given a lot of conditions, such as other components the car has installed, whose catless headers they are (brand), etc. etc. Thus I would caution a blanket statement that removing cats from the headers will release 20hp.

We should also mention that different header designs emphasize different things. Some emphasize HP up high while giving up torque down low or vice-versa, so buyers need to make an educated decision about what they want out of their car and what choice is right for them.
Very true. Outside of the cats, primary length/dia. of the header is the main variable along with
flange and collector design being secondary to performance.
Those could have a dramatic effect on results. Especially torque peak amplitude and RPM.
(since that is all HP is, a calculation from torque and RPM)
Header A doesn't equal header B etc. and in some conditions, stock will be better.
But you can't measure the diff. without standardization of the var.
And, although the cats may be the main issue here, you can't assume that.
And the assumptions are flying in these results.
I've tried to explain this to some as to why the speedart 20+whp dyno is flawed,
but some just want to believe what makes them happy, and that's fine.
But there are significant variables that contribute to these results, and
nobody here is accounting for them or even measuring them for that matter.
Frankly, you would get more accurate results than the dyno comparisons here by just doing 3rd. gear roll ons
on a deserted airfield/road etc with the mod and un-modded cars side by side......
at least you'd be equalizing conditions to the exact same set of variables. (assuming both cars ran consist oil/water temps and equip.)
That's why, unless someone is selling something, the pro's generally aren't on web forums.
This is basically why the SAE went to a standardization and certification program for dyno testing,
because the players had too many biases/self-interests involved in the game and it had to get back to the facts.
 

·
Registered
Joined
·
1,755 Posts
Frankly, you would get more accurate results than the dyno comparisons here by just doing 3rd. gear roll ons
on a deserted airfield/road etc with the mod and un-modded cars side by side......
Funny you say that... planning that right now.
 

·
Registered
Joined
·
28 Posts
Discussion Starter · #10 ·
Aah well, thanks for the chiming in of opinions all. Basically went for the 4 Cat version at this time as I'm not too comfortable with any CEL appearing. Not too sure if I would eventually decat the exhaust even, but that's the route i'm going down now. Long agonizing wait ahead of me for the exhaust to arrive. Ouch!
 

·
Registered
Joined
·
1,755 Posts
Congrats! This seems to be the best exhaust system out there.
 

·
Registered
Joined
·
1,755 Posts
If I am ever in Singapore I will reach out, I want to hear that setup. Are you ading software modifications or just sticking with the exhaust. IMHO, Carpristo alone is a great start.
 

·
Registered
Joined
·
28 Posts
Discussion Starter · #14 ·
Sure, give me a holler. Will be more than glad to play host ya. Am starting with this at the moment first. Looking to add the IPD plenum + throttle body, before I get the software flash on. Am thinking that this may put the hardware modifications to better use since the flash should recognize the differences (e.g. better flowing exhaust) and may help to make better gains.

In the meantime, I could whip out my mini DSLR and try to record some vids once the exhaust is up. :)
 

·
Registered
Joined
·
1,755 Posts
IMHO it is better to take it step by step. Do the exhaust, and see what gains you get. I doubt that anything else you will do will even come close to gains from the exhaust.
 

·
Registered
Joined
·
28 Posts
Discussion Starter · #16 ·
:)

THE box!




Warranty. Can't really figure out how the warranty works though..




The pretty control unit. Such a pity it will be installed and kept out of sight though.




The remote control. Very nicely weighted, feels much heavier than it looks. Fits in the hand like a fine piece of machined item.

 

·
Crusin worlds most isolated city
Joined
·
3,755 Posts
Did you get any damage on the pipes?
 
1 - 20 of 33 Posts
Top