if he got 12 for muffs and tips whats so hard to believe about 15 for the whole set. When you think about it that's not a whole lot. No prob I'm not to good with computers but I'll get the dyno results and post them...

12 whp just from muffs and tips? Doesn't sound right to me. Maybe once you throw in the Ubend delete and downpipe. Stock U bend back is not that restrictive at all.

Think about it if guy's are spending almost a grand for headers and DP and only getting around 18whp which is about 10% increase ,how do you think the cat back which is not all that restrictive would give you 15whp ,naww fraid not ,and though aftermarket muffs may sound nice you're not going to gain much in the way of HP.