I made the baffle for my Mac 4-1 from a piece of metal framing track used in drywall construction.
I cut an 11" piece, cut 5 slots in each side, resulting in 6 tabs on each side, flattened it out, and bent the whole thing into a cylindrical shape, folding the newly formed tabs over each other as I went. Then I drilled a bolt hole in it to line up with the hole in the muffler can, inserted it into the pipe, and bolted it in.
If the new center hole is too small, you can remove it and cut the tabs down a bit. I think I cut each one about half off.
It has been working great for about 3 years. It turned my exhaust from 'ear-splitting' to 'authoritive without being obnoxious.'
If ya need (or even want) more info, I can send ya some pics.
Zip
