What makes this question tough is the subjective nature of the outcome. Kinda like "what's the best color.......?".

I've told my sound quality story many times and I've come to the conclusion that nobody believes it, or it's more thinking than they're willing to invest. But here goes again, short version. I picked up a '40 Ford coupe a number of years ago. Had a mild built flathead, no interior, crappy paint, yada yada. The old bullet shaped glass packs sounded like crap even with full length pipes. Exhaust rehab was at the bottom of a lonnnngggg list of things to be done. In the process of doing the interior I did a full insulation install, roof, trunk, and all. When I fired the car off to pull out of the shop at the completion of the upholstery install I was amazed. I expected the inside sound to change, but when I got out to close the shop door the outside had changed too. Had the bride drive the car up and down the street to confirm. The insulation had dampened the resonance and completely changed the character of the sound from the car. Never did change those tired ol' glass packs.

Similarly, a Flowmaster 40 tale. I put pair on the '64 Plymouth with 440. I didn't care all that much for that Flowmaster echo that I think some mean when they say tinny. Again, after floor insulation and an H pipe added to the full length system that car ended up with the absolute best sound I've ever heard from any V8 car. My '05 Mustang with Magna Flows came close, but not quite as good (cat converters change that game though).

A roadster is going to have a whole different dynamic, sound wise, from a closed body car. I'm convinced it's more than just the muffler and pipes that affect sound.