The 60 dollar China pwk in ebay is your best option. If it's really cold up to a 460 main jet may be needed, down to a 370 if it's a hundred degrees outside. Crazy as it sounds my pwk Jets well from 2-7000 feet from 40 degrees to about 95 degrees . 02 cr250, sst was my least favorite pipe, followed by the fatty. Stock pipe far better than those two, but currently have a gnarly and it is the perfect pipe for this bike. No pipe kills the top end, the gnarly has the best low end , mid, and roll on , I run 182 and a 50 pilot. The big main jet really makes the luggability better than a 175, 178 . My favorite bike ever. And I have several newer 450s
when in doubt, pin it out