I bought a used greddy cat-back SP a few months back and it works fine. The only complaint I have is that when it is in vtec 5000+ rpm, it sounds really raspy and bumblebeeish from the outside. Now my questions are..

1. Does this hurt the performance of the car at all?
2. what is the cheapest way to fix this without spending too much money or getting a new exhaust. I really like the sound of the exhaust for normal city driving but for those times I need to hit vtec, it's annoying.

 

No it doesn't hurt perfromance.

You must modify, new/larger resonator (if it even has one) or get a new exhaust.

A lot of people are opting for the Apexi WS (quite and sleepy).

 

Alot of times the baffle will come lose in the SP or over time the filler used inside the muffler will blow out. I knew a guy who got the sp in 95 on his hatch and used it for 5 years till it got real loud. I just bought one and it's nice and mellow but I know it will slowly get louder.