4" turbo back exhaust?
 

Search function on this forum isn't the greatest and I have been trying to find people that are running 4" exhaust systems on their FC's? Looking for pics and see if there is even room for it.

yeah it will fit, though with some tweaking. one of my customers had a 5" into 4", Y piped into dual 3" out the back off his S475

the 4" was underneath the car to about the where the rear cat used to be.

im doing a 4" dp into 3.5" for the rest...and i think that is tight AF if u dont want to compromise the ground to muffler distance

HKS used to sell a 4" turbo back system

HKS used to make alot of great shit.

I'd kill for their old intercooler kit again.

I am running a 4in DP/MP on a modified RB REV 2 catback, where the Y section was is now a 4in to two 2.5in pipes (or whatever the factory RB pipe size is)

My TII had the 3.5" JIC Spec 90 single exhaust system on it.

It was pretty damn low where the exhaust passes the diff/axle and got a bit of a flat spot there.

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I re-made the exhaust when I went aftermarket turbo with a real muffler/mounts and was able to tuck it up much tighter so it wasn't an issue anywhere I drive (and managed to keep the exhaust from whacking up against the car by using all the stock mounting locations).

I am sure a single 4" is possible unless you run your FC really low and have to negotiate tall speed bumps.

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If you want to split a single 4" into duals you would split into two 3" (well, 2.85" if you can find it) pipes to keep the same exhaust area.

Though, it is not critical to keep the same exhaust area in my experience.

My set-up dynoed the same power figures at the 400rwhp level with 3.5" JIC downpipe/midpipe to RB 3" Rev TII dual rear section (it just weighted 30lbs more than the single 3.5" all the way back). Though, it did make more power at a lower boost with the single exhaust- but with the turbo maxed out the peak power was the same.

I am running a 4in DP/MP on a modified RB REV 2 catback, where the Y section was is now a 4in to two 2.5in pipes (or whatever the factory RB pipe size is)

2.375"