1.5" primaries?

[gasguzzler]

Has anyone tried building a custom header with a pipe size bigger than the common 1.25" OD primary tubes for a 400ex? I'm thinking about trying a 1.50" set-up.

I've got a 12:1 comp. 463/9i web cam FCR carb combination and I'm suspecting my HMF competition series full system may be starting to restrict me (comparatively speaking). My primary use is flat/circle track racing.

Any thoughts?

Thanks,
Brian

[400exwhipper]

Your right a bigger diameter pipe will always give u a better flowing exhaust but the issue with that is gonna be connecting to the motor..and connecting to the slip on and your gonna have to downsize for that and that will restrict flow.. It's a good idea and will probably make more power but its gonna require some fab work with the slip on... Or a custom shorty would be a very good idea

[gasguzzler]

I've got the full system rather than the slip on. I believe the current system is 1.75" back to just after the clamp connecting the head pipe to the muffler. Then it flares to probably 2" before the muffler. I'm thinking go 1.5" primaries merge to 2" all the way back to the muffler.

Thank you,
Brian