2006 6.2 mpi with bravo one,the exhaust bellow,is the kind that slips over the drive when down,and is open in the up postion,I have seen the type that has hose clamps on both ends,which style is better,and why?

I'd use the one that clamps on one end only - much easier to install. Difference?? I've never seen a big difference from one to the other.

which is quitteter ?

The accordion style bellow is quieter than the high performance bellow. The high perf one lets more exhaust out around the bell housing versus making it all go out the propeller hub. If you have an XZ or an XR, I wouldn't use the bellow at all. (some people have replaced an older Bravo 1 with an XZ or an XR that's why I made that statement) Plus from what I have seen the high perf bellow allows more exhaust gases around the back of the boat and makes the transom a little bit dirtier.

John S.