Was thinking of putting a shim kit and shaved heads on my 96 Mach-z 780 , Is it worth it ? they say you get 9hp gain . anybody ever do this

they do work well a good $$ per h.p. value

I've got it in my mach 1,and can say it definitly works.

I'm dooing it to my 94 780 right now. But I'm building all my own stuff. Shimming up the cyls almost 4 mm, building inserts for the head to sit into the bore. Also using modified V-force 3 reeds, my own porting and pipes. Expecting to see 210 hp out of the old girl.

I tried it in a 96 F-III 600. I also had some trail pipes and V-Force. It was dynoed at 138hp at 8700 rpm. It did give some hp on top, but I lost some bottom end, in my opinion. For the next winter, I removed the shims and did a trail porting instead. With porting, it was really better in acceleration and in the trails. Maybe I'm wrong but I think that raising the cylinders also raise the close position of the RAVE valves and they have less effect in bottom end....
With shims it was good from 7000 rpm and up,
W/O shims it was good from 6000 rpm !

I hope it will help.

Motor'n what thickness of shim did you use in your mach I?

It is a .059 thick base gasket from Crankshop.