Horse Power Question-Head Pipes

[kymo99]

I just recently bought a 400 EX that has an FMF silencer on it. However, the head pipe is stock. Does anyone know how much horse power I would gain by ordering a head pipe for it? Will any brand head pipe mount up to the FMF silencer that I already have? Is it worth it to spend the bucks for the head pipe?
Thanks in advance for your info.!
Kyle

[bradley300]

you wont gain anything noticeable unless you have some motor work, the stock header is a very good design

[EXDUNER127]

Buy the powerbomb head pipe from fmf. You do get gains because it has a bigger diamater than stock, they wouldnt sell full exhaust if they werent better. my friend has just a silencer and i have a full exhaust and i always beat i mean always, mostly in the high gears cause that is where the header comes in,
(bottom end). if you have the money get it. i recommend it!