crf 150 r, i guess its not counted as a pitty, but they race them at pitty meets.
but i recon, instead of buying a bloody 5 grand pit bike you should go proper. My Rm80 1999 model, if it was stock it would put out 21 hp. I have some inexpensive mods to it, like a boyesen reed system, and a wiseco oversized piston, probably put out a lil more than 22 hp at least.
but if you have 5 grand, go buy a like 2002-2005 85 2 banger and put som mods on it, most 85 05 mods go for a bit over 2 grand, maybe 3 if its good. but once you buy it put like heaps of mods on it i recon you could probably get like 27-29 hp out of the sucker. But these bikes are much more powerful than pitties, and more fun to ride cuz of the powerband. aqnd they have all proper frames and stuff so you can do the big bike mx tracks and jumps and stuff.