glass packs can sound good and period correct if done properly.i had a set of classic chambered exhaust cobra packs on my 340 dart with an h pipe( 2.5) when it was pretty stock.it got lots of comments on how good it sounded.personally i like straight thru mufflers over chambered(flowmasters) because it seems like everyone runs flow or flow copies.things have changed over the years and my 340 now sports multiple changes including a tunnel ram and dual 3" exhaust with an x-pipe and dynomax ultaflow mufflers.its not nearly as loud as youd think .it looks ,runs ,and sounds like a "muscle car" imo.