First, which is better a high flow cat or a test pipe when combined with my ITR header? also will it make the car sound very much different (louder, deeper etc...) any thoughts appreciated greatly

 

First off, a search would have provided all the necessary information you are looking for. Since I am a nice guy, I will point you in the right direction. This is a thread in the ITR forum that is talking about putting test pipes on their ITR motors.

https://honda-tech.com/zerothread?id=362227


My personal take is that test pipes are awful for the environment, even though the power gains are somewhat better than high flow cats. I too would like for my children to have some kind of ozone left when they are born. Not to mention that I live in CA and getting a car to pass smog is a big deal, and getting caught without a catalytic converter is an even bigger deal/penalty. To each his own.
Good luck

 

thanks for the help