I installed a Perrin catback and cat delete pipe on my Evo last night and what a night and day difference in power. I expected the power increase but I didn't expect it to be this loud. It's not obnoxious or anything but it's definitely louder. I will be taking a couple of videos so you guys can hear how it sounds on stock downpipe. I was hoping it would be as quiet as the APS exhaust but I remembered that the APS has one or two resonators in their piping. The car definitely feels a lot better.

 

Nice, man! Can't wait to hear that puppy. Bet it sounds a lot meaner.

 

I have that catback, is louder than others but i received the horsepower i expected. Looks great. I don't have the cat delete but you can try remove it and test the power i read some thread of people removing the cat delete and this reduce the sound of the exhaust and have no problems with power.

 

Here is a video. I'm debating whether I want to go with a larger downpipe or not. I don't want it louder than it is right now.

VIDEO: Perrin Catback and Perrin Cat delete pipe

 

I started off with just a catback, then I added an HKS downpipe. The car definitely spooled quicker with the downpipe added. If you are concerned with sound, put a high-flow cat on and it should reduce the sound level.