I've been reading a lot online about pipes for my klx250sf and it seems muzzy and two brothers are popular. But which one gives the best performance bump? I'm leaving my bike stock till I take my M test. but the weekend after it's getting a tail kit and pipes and maybe a few other things, and next winter it'll become a 351.

 

I'm pretty sure they'll all give the same performance increase (Not enough for $400!) - it'll come down to how much you want to spend, and how loud you want to be. If I were you, I'd spend the $$ on the 351 kit now and just hack your stock exhaust. No sense wasting the $$ if the performance increase is barely noticeable.

 

There's no replacement for displacement. If you want to get a pipe first, go with the muzzy! The muzzy will give you more power because of the larger diameter header, especially with a 351 kit.

 

idk where you herd this, but from what bill b. said, the stock head made the most? i still say hmf muffler, and any header you like. imho, the muzzy is to big and load for a 250, even with a big bore.

 

I rode another klx with a 351 kit with a stock header and a slip on. There's a noticable difference between them throughout the rev band.

 

care to explain, would be some good info for the rest of us. you have to also remember you feel torque, not hp, so one might have more hp up top if you ran them on a dyno. im hoping this is when bill pops in and owns me with his knowledge.