Basically a header should not be your first mod. Its a support mod. For example.. you will see more hp from cams if u had a decent header as opposed to the stock header.

Not much to be gained from header by itself unless you got the 70mm exhaust to back it up.. it is however a good weight savings mod..

 

ok, i guess gears could be consider as a "bolt-on". but, i'm just saying and this is my opinion, but my definition of a bolt on is any modification that can be done by any idiot with some basic tool. but again that is my definition of a "bolt-on". just saying.

but again gears are very good for acceleration.