Stock Nismo exhaust with forced induction - power loss expected?
 

Hey guys,

I have a TT Nismo 370z making around 500whp on 7psi right now with a full 2.5" true dual straight pipe exhaust (No crossover). The only things in the exhaust are a resonator for each side of the exhaust.

The car is so loud lately that I can't drive it without getting a headache or wearing earplugs.

I'm planning on throwing just the stock '13 Nismo muffler back on the rear of the car so the system goes from each turbo -> 2.5" true dual straight pipe -> each pipe into it's own resonator -> a little more 2.5" piping towards the rear muffler -> each pipe into 1 of the inlets of the Nismo exhaust.

I've noticed the Nismo inlet piping diameter is 2.25", so I'll be using a concentric reducer from the 2.5" to 2.25".

My main concern is will adding the rear muffler inhibit spool / power delivery a noticeable amount? I'd assume no given the nature of the true dual system - each sides' 3 cylinders having at worst 2.25" diameter piping to flow through independently.

Also, would perhaps adding an H pipe into the exhaust configuration prior to the resonators (or after) make sense and help in exhaust flow for turbo application?

It will cost you a little power and torque but you should also probably get it re-tuned because its going to go rich. Since you are at such a low psi I dont know how bad it will be but if you have an AFR gauge then just keep an eye on that to see if you require one. I am guessing you will. You will be adding a muffler to it which are the most restrictive components of an exhaust.

Good to know, the car is actually scheduled for a retune mid next week - which is after this install, so it should all come together nicely :)

You are bound to lose something, how much I have no idea... I am interested in seeing your results though!

Just out of curiosity, would you mind sharing which exhaust you're using that's too loud?

Actually, can you share his you got 500whp ? Must be a bad *** set up. I love all things turbo.

YzGyz

As much as I love the sound of my MXP exhaust, I suspect that it is too restrictive and holding up power. Being that I had to modify the exhaust for the BP setup (Basically cut the Y )

Would adding restriction tend to create more backpressure ergo holding higher boost?

Yes = Bad.

Made 600whp 12psi on TT 370 with stock NISMO cat back exhaust, no problems, but just removed it for a 3"FI and boost went up and had to adjust the tune calibration.