hey guys i currently have a custom twin underseat exhaust setup on my nc30 i am just wondering how much does it alter the engine performance if i shorten the exhaust headers themself?
cheers Tim

i think a lad with the Forum name oily is one of the only regular forum members that did the underseat exhuaust mod. best to PM him i'd say.

I wouldn't if i were you mate, it can't do it no good, i suppose they're the length that they are for a reason.

My friend shortened mine and i gained about 1.2bhp BUT i don't know if the new shortened carbon fibre exhaust played any factor in it or it was a combination of the two but i didn't complain

yer i have heard that if u change the lenghth it can alter the power in either low range mid range or high range revs, the pipes from the back 2 cylinders (closest to rear wheel) look pretty ugly but i guessed that its so they ar roughly the same length so i guess i will just leave it and put a guard over it to hide the uglyness haha cheers guys

Exhaust length tuning is a black art and can affect the performance dramatically.

A rule of thumb is that longer pipes suit lower rev range perfomance and shorter pipes the higher rev performance. Get googling - there are lots of "tuned length" articles out there.

I would not chop it unless it was a trial system and you could revert back to std if you cocked it up..

Tim,
Pictures & details of supplier please!!!
Twin underseat sounds VERY interesting!
Thanks!

its a custom made underseat setup made from old exhausts chopped up and welded together i have compared it to the stock system and the power delivery seems to more better in the mids then stock :) so im pretty happy with that as for power output wouldnt be any better, that with an open airbox setup and carbi jetting to suit im pretty happy with the way it runs :) just wondering if i changed the lenghth between the two different exhausts if they would perform different :)will post pics shortly