I've had 4 mustangs my first 3 had flowmaster. So with my current one i wanted to try something different and went with slp. Money gone to waste, 1000 miles later and flowmaster went in. I've heard lm1 & lm2 and flowmaster on a 97 cobra with an o/r h-pipe. The flowmaster gets a LOT more compliments than slp. That's my experience. There are better mufflers out there but flowmaster sounds better than slp