Stew , not to knock you out of a sale , but just to ansure a question ...
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SpringMan
I'm using a 12" shorty. The thing is you need to put a DB Killer in each end of it or there will be way too much noise.
So.
One end has 1.75" ID and the other has 1.5" ID . Order one of each when you order your muffler, and throw away that little piece of $#!& that comes with the new muffler.
Something really good about using the 12" Shorty is the weight . They weigh next to nothing and 2 DB killers don't add too much.
The factory muffler hanger will keep you from loosing the next one ... that muffler clamp by itself will never be enough. You know you are liable for any pieces that fly off your machine ...

I'll post a few pictures for ya.