I'm looking at exhaust manifolds choices for my R1 (5PW)

Can someone give me an idea on the difference of power delivery between a 4-2-1 and a 4-1?

4:1 is designed for peak torque/power at a set number of revs.

4:2:1 provides a better torque spread across the rev range but achieves slightly less peak power (this is the one to go for).

When you buy the headers the supplier should be able to tell you what rev range etc the exhaust is designed for, if they cannot then its just shiney pipes !

Loads of variables, by playing with bore size (primaries should be 15% bigger than the port they cover), length to first silencer, shape of collector (this should not be pipes bent into a Y but a proper conical taper with the pipes entering squarely) you can rock where the peak power occurs by playing around with all of these.


Regards Mark

[Edited on 23/4/06 by mark chandler]