GC8 Straight Pipe Exhaust

[snwmbl]

I would like to get a straight pipe but was wondering how much of the exhaust I can change before it'll affect the tune? At the moment its a full 3" exhaust with resonators/large rear muffler from a Garret gt35. I was thinking of ditching the rear muffler and having a rear section 3" straight pipe fabricated to bolt onto mid pipe.

[ADIKT]

Will be fine

[lachlan]

depending on your boost controller it might need fiddling . other than that it will only run better .

[snwmbl]

Got a link g4 controlling it.

[Guest]

Get it tuned. At gt35 level losing 2-3psi of post turbo pressure could cause issues. Wouldnt cost much to strap it down and spend an hour tweaking ****.

[hang009]

If you do eventually go straight pipe, I say put a 10 hr vid up of your new rumble (:

[snwmbl]

I can do that.

[lachlan]

 evowrx said:

Get it tuned. At gt35 level losing 2-3psi of post turbo pressure could cause issues. Wouldnt cost much to strap it down and spend an hour tweaking ****.

why do you say that ? g4 is closed loop boost controll . couple of easy pulls to see if there is a boost overshoot and allow it to fix it .

other than boost controll i struggle to see how less exhaust back pressure is going to effect an engine or tune ?

less back pressure = less exhaust in the cylinder so more fuel and air in the cylinder ? if that is even possible i dunno

[Guest]

Well .2-.3 afr between p18 and p20 on same tune make your own judgement.

[nztintin]

From my experience on a 2.5" exhaust and running a g4 and running a straight rear section it doesn't effect the boost much, my car has a very low boost cut threshold over the boost set point and I didn't get any extra issues running the straight rear section, I get more issues running the car on a real cold day.