Back when I had my 87 250 I tried an fmf, turner mid and a turner rev pipe on it. It was stock as far as porting goes. I felt like the turner rev was the best, and the fmf and turner mid were a wash. I honestly didn't think there was that big of a difference in any of them though. I sold the bike to a buddy of mine that was racing mx at the time and gave him all three pipes to try. When I talked to him about it a month or so later, he said the same thing. Not much difference, but thought the turner rev was probably the best overall.