How to quiet down my 3" exhaust?

jbc426 said

I swapped a set of these into my '68 when it was too loud.

Super Turbo™ Mufflers - DynoMax® Performance Exhaust

Click to expand...

Aren't those the same as the Summit turbo mufflers though?

How about another pair of turbo mufflers in place of the glasspacks... any problem with putting them in series?