car chemistry inserts

anybody ever run these on a sbc,i have clearence problems with my exhaust routing and am considering tring them out,how loud shound i expect them to be.

http://www.carchemistry.com/ccflanged_inserts.html

 

i had to run mufflers similar to these on our dirt latemodel race car. it had a 440" small block chevy. some tracks close to town required them. i couldn't see the point since i couldn't tell any differance in noise level. but they say if you put a decible machine to them it does make a differance. but it's still going to sound like open headers.