Bills Pipes have been around for a while, and from what I hear they make a good product. I can't remember, but I think I rememder reading that the Suzuki 2 strokes are their forte.
My 02 250 had a Bill's with the shorty silencer. It was a midrange powerband. Decent low end a strong mid and a good top end. Cunstruction quality was great and it seemed pretty dent resistant. I'd recommend one.