yea i just put a flowmaster muffler on my 94 sl. It is a 40 Series Flowmaster muffler (original flow not delta) Anyways, the stock piping on the sl is 2 1/4 ". So I deleted everything from the cat all the way back. I then replace this with 2 1/2 piping running into a a single in/Dual out flowmaster muffler (that 40 series). I then had 2 1/2 piping running from the dual outlets to the big 4 1/2 tips i have. Any more questions Message me private.