Exhaust header port matching

[PAvector]

Surprised to see how poorly matched the exhaust ports are to the header. Is there any concern about opening up the entry of the header and removing some of the tube edges so they match better with the exhaust gasket. Thoughts?

 

[cannondale27]

Go for it! Stock header?

 

[PAvector]

Yes, picture is stock header. I actually think the ID of the header tube is smaller than the head port.

 

[cannondale27]

Yes, picture is stock header. I actually think the ID of the header tube is smaller than the head port.

That’s not good! Nice catch. Need to look at mine now.

 

[PAvector]

Head exhaust ID is 35mm and header tube ID is 31mm

 

[Snorunner]

Better flow is good. But don't forget about back pressure.