38mm to 40mm exhaust port

[vanzen]

How about 45mm pipes? Is this just a sales gimmick?

RB headers start at 38 mm to fit the port, the diameter then expands twice, by looking at pics of the product, to 45 mm ...
A gimmick ? NO !
The theory of an expanding diameter head-pipe works.
Can you reproduce positive results by arbitrarily mucking with your exhaust ?
XD.
IF the diameter and rate of dia increase will be CORRECTLY CALCULATED AND APPLIED –
the theory works.
Want to play with it ?
You will be renting time on a flow bench, a dyno, and on the track –
or you may as well be pissing into the wind.

[awaffa22003]

Yep, have access to his dyno too. And wow this is really great stuff guys. I thought expanding headers were only applicable to 2 strokes with expansion pipes. Is it the same idea with the exhaust pulses IIRC?

[Chuey]

I just thought my idea was cheap, expedient and kind of fun compared to some other options. If it isn't a fire breathing monster, don't blame me, please. What you tell others is up to you.

Chuey