I'm surpised with all the hating on Flowmasters, Does anyone really think you can add tons of the HP with a simple catback? please all of these catback that we install are only for sound and looks. I said this a dozen time GM has spent tons of money researching and creating the best performance/fuel economy combo do you really think a $400+ exhuast system is going to out smart a room full of engineers? just my $.02