exhaust size

[sfron03]

some local guy is selling a custom 3.5" exhaust with a greddy muffler. i was just wondering, if there is any pros or cons of having 3.5"? i know that most people go with 3".

 

[RedGSX21]

thats pretty big man. people use only a 3inch exhaust when they are going for high horsepower. I dont suppose it would hurt the performance imo i think it would be fine the less restrictions in the exhaust the better so i guess it would be great. lets here some other opions tho.

 

[sfron03]

did you mean 3.5" or 3". i see alot of people here running 3"

a couple people have said that 3.5" might hurt performance. but they aren't too sure.

 

[RedGSX21]

did you mean 3.5" or 3". i see alot of people here running 3"

a couple people have said that 3.5" might hurt performance. but they aren't too sure.

i was talking about the 3.5" exhaust. I have never heard of anyone talking about putting that large of an exhaust on their cars unless maybe it is racing only or somthin i guess. Many people do put 3" on their cars. Im wonderin why 3.5" would hurt performance tho.

 

[RyanJ]

with a turbo car you should be fine your not really concerned with scavenging like N/Ts are I say if youre looking to move massive amounts of air through that thing then go for it.

 

[No_Skillz]

3.5 is not harmful to performance. However, it is total overkill and such a massive pipe running underneath your car might get in the way of your rear suspension. Make sure everything fits before you go for it.

 

[98gsspy]

No_Skillz is right. But I wouldnt get it because it might make your car sound very drowny or a "fart can" as I like to say it. I would stick with 3"

 

[sfron03]

well, the local guy replied back last night and said it is NOT good for stock turbo, as it will cause the turbo to overspin. . thanks anyways

 

[GVR4592]

well, the local guy replied back last night and said it is NOT good for stock turbo, as it will cause the turbo to overspin. . thanks anyways

The guy doesn't know what he's talking about, it won't hurt anything.

 

[zippyshoe]

The one item you may be more susceptible to is boost creep. But don't let this stop you from going with a 3.5-inch exhaust - however, you may need to port your turbo's wastegate passage as well as your O2 housing depending on the type of turbo you are using/will be using and what boost pressure you plan to run.

 

[Killa95GS-X]

it wont hurt at all, its just a little big. 3'' is perfect, 3.5'' not needed on a street car, and it will not over spin the turbo or what ever the guy told you. and you dont have to worry about backpressure to much a turbo car because the turbo acts as a muffler in a way. i ran my gsx with an open 3'' down pipe for a day and it wasn't even that much louder at all and it felt like it had a little less backpressure but nothing like taking the exhaust off of a naturally aspirated car . but i would only buy the exhaust from him if he is selling for really cheap other wise just get a 3''.

nick

 

[Knockin1g]

it wont hurt at all, its just a little big. 3'' is perfect, 3.5'' not needed on a street car, and it will not over spin the turbo or what ever the guy told you. and you dont have to worry about backpressure to much a turbo car because the turbo acts as a muffler in a way.

"Over spin"... haha! He's reffering to boost creep. And you DO have to worry about back-pressure, or in this matter, the lack of it. If you're running a 3in with no cat (let alone a 3.5in!) on small turbos like t25's, 14b's and 16g's, boost creep is almost certain to some degree unless you have a properly ported turbo.

 

[Killa95GS-X]

yeah you may want to port 02 housing if you decide to use it. i didn't get boost creep on the evo III when i did it but all cars are different and like he said the smaller turbos will probably get some boost creep.

nick

 

[SinaiTSi]

3.5" is a little excessive, but at the same time it won't hurt anything. If you get a good deal on it, might as well pick it up. If you run a huge turbo later down the road, you might even see it beneficial. I'd actually really like to see someone with a 450+ hp car dyno with 3" and then with 3.5". Might be a pain, but it would be cool to see outcome.