[Ant]

scottj,

With using a 3.5' perforated muffler core, are you running a 4.5' OD sidepipe?

Also you mention the noise is similar to a straight pipe, I dare say the only way to quieten for certain situations is to plug a chambered type baffle up the the end or inside the muffler, but that would have to go down to maybe 2.5" for the street, and still have the lack of response with a big cammed engine like mine!

Another thought for packing a muffler is a product here called KAWOOL is the white mildly toxic (strong coffee) fluffly dense wool they wrap around boilers can stand a great deal of heat, but its normally behind a metal skin not in direct spark type exhaust flow!