How big of a difference does a 3" downpipe make?

[ZavzTy547]

Are the 3" downpipes a "significant" HP gain, compared to the stock 2.5?
The reason why I ask is because I know a seasoned SYTY guy that can build me a hybrid TE-62 and mate it to bolt up to the stock downpipe. I already have a 3" cat with custom exhaust and rather not modify it for the PTE DP setup, plus I could use the extra 6 bills to buy injectors and rebuild my suspension.

Waller didn't you us a hybrid setup with the 2.5 dp?
Any boost control issues?
Thanks

 

[Six-is-Enough]

I went from the stock dp and cat to a JS Manufactoring 3" Donkey Down pipe and dump, I don't know HP diffrence, but it went from a 8.22 1/8 @ 80mph to a 7.78 @ 88.


This was with a stock turbo. Just make sure you do some tuning to control boost spikes or swicth boost contollers.

 

[ZavzTy547]

That's a big increase....

 

[Six-is-Enough]

I thought so too. I would Imagine that gains would even be greater with a larger turbo.

 

[Jer]

Decreased back pressure will allow for quicker spool-up of the turbo and allow for more airflow at higher RPMs which will allow it to continue to bulb power to redline where a stock down-pipe and exhaust will fall on it's face half way through the revs and the power will plateau. So, decreasing the back pressure will give you better turbo response and you'll also feel a seat-of-the-pants difference on how it pulls to red line too.