Hey everyone!
Just a quickie ... Can any one tell me if the header pipes on an XB9 are the same diameter as an XB12. I understand that European models have recently changed but are the two models different.

... and if they are as I believe smaller is there any advantage putting the larger bore pipes on my 9

No, the 9 pipes have a narrow diameter to the 12 ( IIRC 42mm on the 9 and 45 mm on the 12 - but not sure ).

I don't think that there is any advantage to using 12 headers on a 9 unless the engine has had extensive modifications - but then again that is only my opinion.

IIRC there was a test posted on the old forum that showed the key to an XB9 was a well-designed end can

Thanks everyone!