I'm a college student looking to free up my stock muffler with a replacement fix that is a little more free flowing. Don't have a lot of money want to put a glass pack on instead of flowmaster. I want the best bang for my buck$. Im just curious if a glass pack is to free flowing or if there is a certain amount of back pressure you want to maintain. Have a k&n air filter on order. Just want to free this great motor up a bit.