This is an old thread but found it when searching for options..just thought I would share what I did. I ordered 2 Thrush 24210 from amazon for about 32 each. Then bought 2 12" long tips 2" diameter from Autozone $10 each. Welded the tips on..then welded a strap on top of the tip to extend to the mounting bracket. They sound pretty nice with the cat removed.

 

Decided to add a couple of pics..this is with BBQ paint..they are getting ceramic coated now..