I have a honda 250ex and I want to put a pipe on it and re-jet the carb. Does taking the airfilter box lid off give you more power.

 

Ive seen an ad for carbide's motoworld selling a whitebrothers e-series slip on exhaust but thats it and it may even be a misprint. Dyno sells a jet kit for the 250 too. Other than that i dont know of anything else.

 

4 strokes don't use tuned pipes, only 2 strokes do. Tuning a pipe is changing the length and width of an expansion chamber to match the required harmonic resonance, of a particular 2 stroke motor or powerband. All they do with a 4 stroke pipe is make it less restrictive, no science there. I think the whole 4 stroke pipe industry is a scam, they should only be gettiong about $75.00 for a whole system.