s4 tii bridgeport engine with n/a rotors and 60-1 t04 turbo. I have a 3in dowpipe which deletes the two precats and a borla muffler in place of the main cat. After that muffler the piping goes to the stock size 2.5? to the magnaflow muffler. Would that cause alot of flow problems? Reason im asking is becuase the power is kindof low for a bridgeport and only gets to maybe 10psi with a boost controller and 10lb spring. Doesn't seem like the wastegate is opening either.

 

Nobody? Im just trying to get an idea of what size it needs to be so I can be looking around.

 

i have a 3 1/2 turbo back on mine with a NI single exit exhaust running a 62-1 with a 1.15(NA rotors),boost starts to build up around 2200 rpms and it holds 15 psi steady all the way to redline and if stays there if i dont get of the gas,if i stay on the gas it keeps building boost,i love it.

 

Yea I see all these threads about 4 and 5in exhaust and would love to be able to stick with 3.5 with the performance. This 3-2.5in exhaust is killing me though.

 

the 2.5 is holding your power back,what size housing AR do you have?is a divided housings?on center?non divided?

 

Install a QTEC......problem solved while maintaining a quiet daily driver as well. http://s222.photobucket.com/albums/d...ortexhaust.flv

 

I haven't actually measured the hot side but i'm pretty sure it has .8 stamped on the housing. The manifold is the hks cast iron one which is non divided and the turbo has the divided housing.

 

Sould getting a 4in be better in the long run instead of 3 or 3.5 or is that plenty enough for like 400hp?

 

i run a 4 inch on a half bridge... its kinda loud

 

^What kind of muflers do you have?

 

you have all sorts of choke points in the exhaust system. 3" downpipe to a 2.5" catback, small divided turbine housing to an undivided manifold... be careful though, the HKS manifold is prone to boost creep. if you open the exhaust enough you may have some problems unless you have a large wastegate (the HKS 40mm will definitely creep at 10psi, it did on my streetport).

 

2 magnaflow cans in series

 

So would changing that 2.5 section to 3in be okay or would it be better to just change the whole exhaust to like 3.5in?