I forget who, but someone does make a multispeed tranny for the Baja, What I remember is it being ridiculously expensive with moderate performance gains. A tuned pipe ( I recommend the DDM Dominator or the GBE pipe) is a must for any Baja. That and a well adjusted carb and you should be good.Also, you didn't mention what engine you are using. a DDM modified 30.5cc ported one would be great.