I've got a dual Flowmaster setup on my '91 that I love. It's a single series 40 Flowmaster muffler with dual pipes running from it. On some Explorers they apparently have to take out the spare tire to get it in there, but that wasn't the case for me, they went around it. It sounds great, and the dual 18" long 3" chrome pipes look great. If you need anymore information, drop me a line.