could some how make 58 or 60mm tb's with the barrel method. The thing is a lot of people are having issues with the z1 tb's. The issues that I know of are sticky plates(they get stuck shut), leaky shaft seals and plates that don't seal very well causing the idle to be too high. I think many members with 2.5" piping would be interested but only if your upgraded tb's were free from these issues. The good thing about stock tb's are that I've never heard of the shaft seals leaking.
