I used the Pro Circuit platinum 2 pipe on my 03 RM250. It is a pipe for off road but worked very well for me as a beginner motocrosser. It gave my bike a whole lot more bottom end, which is what 2 strokes lack anyways. The bad part about that is that it takes off some power on top. I did'nt mind because I never really used that much top end on a 250 2 stroke. I liked it the best out of all the 2 stroke pipes I had because it gave me more usable power and did not hit like nitro when the powerband kicked in. Made the engine powerband more steady from low to high.
The Platinum 2 is very different than the Platinum.
Just a novice racers opinion, so take it for what it is worth.
http://www.partsmag.com/0304/Pro-Cir...cuit-0304.html