Exhaust question!

[nissanper]

Hi!
I have checked around for too long I think for searching how much a 3 inch exhaust will increase the HP!
So my question will be this!
How much HP do you gain with a 3 inch exhaust system with catalytic converter? HKS is what i have and with a 5 inch catback!?

[Chaluska]

well a 5" catback would definitely be more free flowing than a 3"

I am willing to safely bet you will gain at least 1 hp from a free fowing cat-back exhaust system.

[Walperstyle]

Please explain why you need a 3 inch exhaust? ...let alone a 5 inch catback

First rule of making power. Bigger is not better.

[nissanper]

I think I've been un directley so i will explain differently.

This is what i HAVE:
HKS manifold/header, the one peace right after the downpipe is a double barrell pipe of some sort. And I have HKS 3" all the way back to the cat-back witch IS a 5". I am only curious of what i have gained from Stock exhaust.

I'm curious because i'm going to show my car to the government and i have SR20 in my s13 wich is NOT allowed in Norway (stupid I know) and therefore, how much power will i loose cause thats my goal! they're stupid so i might have a chance to get it through cause they dont have a clue, but they might also se different parts and check it closer and FIND out! and if they test the car i will have as low power as possible1!

[fliprayzin240sx]

Crank the boost down to as low as you can to get the run to run "stock-ish".