Anyone remember or use "Sonic Turbo" mufflers?

They are a classic "Turbo" muffler, much like many available today, and at 3" they should also flow more than enough.

They were not however the first "Turbo" mufflers. "Turbo" mufflers were first installed on the 1962 Chevy Corvair Monza Spyder which had a turbocharged engine. Hotrodders soon discovered that the Corvair mufflers flowed great and weren't super loud. The aftermarket has been making mufflers in this basic pattern ever sense. The "Turbo" reference actually has some historic significance and was not just 80's marketing hype (plenty of other things said turbo in the 80's).

Mopar also made a free flowing fairly quiet muffler which was popular with hotrodders. They originally came on Hemi cars and are commonly called "Hemi" muflers. By the 80's the "Turbo" name was winning out, giving us the "Walker Hemi Super Turbo" which was in fact a Hemi muffler and not a Turbo muffler.

In the 90's some clown came up with the "Flowmaster" which didn't flow any better, but made a lot of noise sounding like a rusted-out version of either of the above.