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Discussion Starter #1
I have the FVD Brombacher switchable/valved exhaust on my Cayman GTS (love it by the way, still trying to make decent videos with something other than an iphone, it sounds amazing) -- any reason to believe that there would be any changes on the GT4 that would preclude swapping the FVD exhaust onto the GT4? (such as different size/length headers and/or catalytic convertors, different angles/geometry of the joints, etc?). Wondering if the GT4 exhaust is the same as the Cayman GTS PSE or something completely different and I won't even want the FVD. I am assuming it would be a direct fit, anyone have any guesses?
 

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I have the FVD Brombacher switchable/valved exhaust on my Cayman GTS (love it by the way, still trying to make decent videos with something other than an iphone, it sounds amazing) -- any reason to believe that there would be any changes on the GT4 that would preclude swapping the FVD exhaust onto the GT4? (such as different size/length headers and/or catalytic convertors, different angles/geometry of the joints, etc?). Wondering if the GT4 exhaust is the same as the Cayman GTS PSE or something completely different and I won't even want the FVD. I am assuming it would be a direct fit, anyone have any guesses?
Differences in the rear suspension, inverted struts, rear wheel hubs been moved inwards, hopefully better cooling for the tranny/diff, better cooling for the rear brakes. Take any of those guesses as possible reasons why an exhaust designed for a 981S/GTS might not fit properly on the GT4.

Why wold you opt for a FVD if the GT4 comes from the factory with a PSE? Sell the FVD and get more funds for the GT4, that is what I would do if I were in your shoes.

Update:

One more very important point. If you are going to track the GT4, it might be possible that you might run into situations were the FVD even in quiet mode might not pass sound restrictions that are imposed at the racetrack.

Update:

Not sure if the following picture from the German GT4 Catalog will help you in determining if a 981S/GTS exhaust will fit on a GT4. But something is better than nothing..
 

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Discussion Starter #3 (Edited)
Differences in the rear suspension, inverted struts, rear wheel hubs been moved inwards, hopefully better cooling for the tranny/diff, better cooling for the rear brakes. Take any of those guesses as possible reasons why an exhaust designed for a 981S/GTS might not fit properly on the GT4.

Why wold you opt for a FVD if the GT4 comes from the factory with a PSE? Sell the FVD and get more funds for the GT4, that is what I would do if I were in your shoes.
My GTS came from the factory with PSE and I ditched it for the FVD valved exhaust for something a bit more aggressive while still retaining the factory exhaust controls in the center console. The PSE sounded good on the GTS, but the FVD just sounds even better, but still isn't crazy like the Armytrix or IPE. If the PSE on the GT4 is the exact same as the PSE on the GTS, I will just put the old PSE back on my GTS (I never sold it) when I sell/trade the GTS and put the valved FVD on the GT4.

Update:

One more very important point. If you are going to track the GT4, it might be possible that you might run into situations were the FVD even in quiet mode might not pass sound restrictions that are imposed at the racetrack.
I'm not too concerned with that.

Update:

Not sure if the following picture from the German GT4 Catalog will help you in determining if a 981S/GTS exhaust will fit on a GT4. But something is better than nothing..
Thanks for posting the photo, when I compare the illustrations (see below, sizes aren't quite perfectly matched, but you get the idea) -- they sure look identical at first glance, but of course can't rely on that. I'll just have to wait and see. Thanks for your input!
GT4 vs GTS.jpg
 

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Why would 3.4 Cayman exhaust fit on a 3.8 911 engine? Am I missing something obvious? why do exhaust dealers sell different exhaust models for the different engines?
 

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Why would 3.4 Cayman exhaust fit on a 3.8 911 engine? Am I missing something obvious? why do exhaust dealers sell different exhaust models for the different engines?
1) See Pete's post on engine commonality.
2) Because they can since people expect differences.
3) Who knows
 

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Why would 3.4 Cayman exhaust fit on a 3.8 911 engine? Am I missing something obvious? why do exhaust dealers sell different exhaust models for the different engines?
I think you're asking the wrong question... If you had the opportunity to design and build both the 991 and the 981, why wouldn't you design them to share as many parts as possible?
 

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different engine. Porsche guy on evo YouTube video said they were challenged to make the 3.8 l fit. I'd say 90% chance the gts exhaust won't fit, but those images do give you hope. Good luck...maybe you should sell the gts exhaust to me!
 

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Sportwagen, why? Because I don't work for GM! :burnout:
 

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Discussion Starter #10 (Edited)
Why would 3.4 Cayman exhaust fit on a 3.8 911 engine? Am I missing something obvious? why do exhaust dealers sell different exhaust models for the different engines?

different engine. Porsche guy on evo YouTube video said they were challenged to make the 3.8 l fit. I'd say 90% chance the gts exhaust won't fit, but those images do give you hope. Good luck...maybe you should sell the gts exhaust to me!
I thought it seemed pretty reasonable to assume that it's the same spacing/geometry for the exhaust components to be interchangeable between S/GTS/GT4, since it seems BGB's 991 3.8L swaps are using the stock 2.7/3.4L headers/exhaust (or aftermarket headers/exhaust intended for the 2.7/3.4L cars). Not to mention the illustrations look identical. The way BGB seems to be able to mate the 3.8L to the 3.4L chassis and transmission with relative ease, I was under the impression most of the guts of the engine were dimensionally identical (externally) -- just higher displacement (internally). Time will tell, I suppose. If it doesn't fit, I'll have an FVD valved exhaust to sell!
 

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Sportwagen, why? Because I don't work for GM! :burnout:
I think you have to keep in mind the role the Boxster plays in Porsche's recent history. The reason why the 986 was a financial savior for Porsche was because it shared so many parts with the 911. Porsche was able to increase revenue by adding a whole new line of cars, but they didn't actually have to finance building a whole new car.

If anything, component sharing is *more* important for a small company like Porsche. A big company like GM can create unique components with spare change.
 

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i think . not sure ..but gt4 has only mode.. and its loud.. they did that to save weight.. if you look at configurator there is no pse.. option..

lemon
 

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i think . not sure ..but gt4 has only mode.. and its loud.. they did that to save weight.. if you look at configurator there is no pse.. option..

lemon
Nope. It comes with PSE, standard. That's why it's not an option.
 
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The ports are the same on the 2.7L headers as they are on the 3.4L headers as they are on the 3.8L headers on the OE front. Economies of scale. There are so many interchangeable parts. I am pretty confident that whatever mufflers you have for your 981 will swap directly on your GT4 as would any headers you already own.
 

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Discussion Starter #18
The ports are the same on the 2.7L headers as they are on the 3.4L headers as they are on the 3.8L headers on the OE front. Economies of scale. There are so many interchangeable parts. I am pretty confident that whatever mufflers you have for your 981 will swap directly on your GT4 as would any headers you already own.
Thank you!
 

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Why would 3.4 Cayman exhaust fit on a 3.8 911 engine? Am I missing something obvious? why do exhaust dealers sell different exhaust models for the different engines?
Remember that all of the DFI motors are almost 100% identical with the exception of the obvious stuff like the crank shaft, pistons and the combustion chambers. The exhaust port face is the same. When it comes to Caymans and 911s though, the exhaust manifold is dictated by the application. A Cayman/Boxster setup that has over-axle pipes requires a Cayman/Boxster manifold when a 911 engine is put in the mid-engine chassis. That same motor would use a 911 manifold if it was put in a 911. All of the Cargraphic, Fabspeed, FVD stuff has bigger ports and therefore those vendors can make the argument that they are for larger displacement motors but the reality is that the same aftermarket manifold for your 981 3.4L will work on your GT4 and that all of them are just putting bigger ports on for 3.4L and 3.8L cars.
 

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This thread is akin to asking what Scarlet Jo's breasts are like. We can all describe within a certain degree of probability but until someone puts their hands on them -- err, I mean on a GT4 -- it's all really speculation, isn't it?
 
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