how does it sound.

 

What do you want to put it on? How are you going to use it: Single in stock location? Duals on long-tubes? In place of cat?

I have a pair of the 3" header mounts on the '57. 2-1/2" tailpipes to the bumper. One word describes them well - loud.

In the stock 3rd gen, single muffler location, about the only benefit they'd provide is noise. If that's what you want, then go for it. In the cat location, they may function marginally as a cutout (I'd imagine mounting would be a nightmare).

I've only run them uncorked once - gained almost two tenths in back-to-back corked and uncorked runs. Don't blame the tailpipes, I ran half the season without the pipes, no loss when I had them put on (except for a substantial noise reduction in the cockpit). My conclusion is the mufflers are loud and restrictive when corked, easy to uncork and really loud at the track.