whats the advantage with a 3" system over smaller sized pipes??
would car need mapped?
scooby-93
23 October 2008 06:58 PM
it would needed mapped if you removed the down pipe. but not if you only are going to get a cat back. with a 3" turbo back i have been told that you can loose too much back pressure therefore low down torque is lost compared to a 2.5" system. if you are after 340/350bhp+ get a 3" if not 2.5"
adzer
23 October 2008 07:20 PM
its just that i removed a system off my car and put it in my shed and put on my smaller system coz i liked the look of the angled rear silencer.
so not sure if i should put the 3" system back on or sell it and make some money for my rebuild?
help2003
24 October 2008 01:27 PM
What year is the car?
i removed my 2.5 and went for a full 3" decat system which didnt need a remap, and it pulls alot better and the noise is great
adzer
24 October 2008 02:35 PM
93 WRX RA MATE
silent running
25 October 2008 09:56 AM
Originally Posted by scooby-93
(Post 8218533)
it would needed mapped if you removed the down pipe. but not if you only are going to get a cat back. with a 3" turbo back i have been told that you can loose too much back pressure therefore low down torque is lost compared to a 2.5" system. if you are after 340/350bhp+ get a 3" if not 2.5"
No turbocharged car needs or wants ANY back pressure at all downstream of the turbo. The rules of NA cars where you might need to tune runner lengths in your manifold, experiment with 4-2-1, 4-1 designs etc are mostly thrown away. As long as you can get fast, even gas flow up to your turbo, from there onwards the best solution would be to have no further exhaust at all AFAIK.
The drawbacks of a 3" system over 2.5" are basically noise and possibly weight depending on how it's constructed.
