I tried searching but I was wondering if anyone has done before and after dyno tests with stock exhaust and then high flows...

 

Your best bet is to save up and get majority of the mods u want bc no one is crazy enough to buy 1 part at a time and waste their money on a tune for each upgrade. This isnt NA anymore where u can just buy 1 part at a time and expect not to go lean and BOOM .

Cats arent going to give u much pw if u dont change out your whole exhaust.

 

we have a few times, really didnt make any difference with high flow cats and test pipes. same hp range, little more or less boost depending on which ones.

 

Are you saying there's not much difference tp vs hf or are you saying there's not much difference between stock cats vs tp/hf?

 

http://www.sccoa.com/articles/cwexhaust.php

Around 5 psi in front of main cats at redline is a good number. Each psi [measured after manifold before cat] of back pressure is roughly equal to 2 HP left on the table.

Very very very loud designs maybe ~~ 4-5 psi. OEM cat typically have a 2-3 psi backpressure and the exhaust system adds 2-3 psi

http://www.tomorrowstechnician.com/tt/tt020526.htm