Does any one out there feel like measuring their new Akrapovic/Hindle/god knows what - exhaust for me?.....I would like to know the "ball-park" header length and diameter of the new systems that people fit to their birds - measure from the cylinder head to the point where it merges into the other header pipe in the collector?.....this would be very interesting to know! :wink: .....or does anyone know of any sites where the header dimensions are quoted? :sad:

I have a Dyno session planned early next year and am intending to play with the exhaust length in order to find a few hp, It is a full stainless system with a 27.5 inch header, made from 1.5 inch diameter pipe. I was advised against using 1 5/8 diameter pipe as aparrently is would have killed the mid-range power. :evil:

I forgot to mention - has anyone tried a stepped header design? - like the type from Ti-Force - if so I would be interested to hear how they perform .....with dimensions! :lol:

Yosh RS 3 race 4-2-1,1.65,2.1 and 2.25 OUTside D.
I took all this with pipe on the bike with plastics so lenghts are -/+ 1 inch,primary is 22.5 and secondary is 6 inches long so if it is 4-1 pipe you are in the ballpark.
Stepped header would improve low and midrange without killing topend.
You would want to start with 1 3/8 then 1.5 and go to 1 5/8 I.D headers.
I don`t know if anyone makes stepped pipe for XX .
I have stepped ti Duplex 4-2-1 Yoshimura on my R1,pure art,even lost part of header right before muffler is stepped.
BTW Akra has 38 mm primary I.D. pipe.

Thanks Tomek - thats very helpful - my system is a 4-2-1 the reason for the long header is that the exhaust now runs alongside the RHS clutch/timing chain side of the engine (engine now in a race car!) - The Yoshi sounds like it runs a much shorter header than my system - I have previously been told the magic figure is a 24-1/4 length primary - I can take about 3 inches out the length to meet this, so thats what I'll have to do!.....Whats a BTW Akra?.....

Have you had your bike dyno'd? if so how does the exhaust perform? whats the midrange like compared to the standard system?.....and what sort of top-end figures you making?.....would be interesting to know!......a company called Ti-Force make a titanium stepped header system for the Bird - on their site they quote about 142Bhp at the wheels - which aint anything special in my opinion!

Anyone out there feel like measuring their Akrapovic system for me?.... :wink:

It sounds like you running long primary,but lenght of secondary pipes counts too,acually they need to be added up to speculate.
Second thing, aftermarket pipes might not work well in your case since it is some kind of race car,I bet it weights more then XX.
You might want to give up some topend power for stronger midrange,XX is relativelly weak in the midrange,good powerband is from 7-11K rpm.
Peak power figure tells very little how well pipe performes,nice torque and decent topend it is what counts unless you are drag racing.