Any kind of aftermarket muffler is probably going to be too loud for you. I have cheap turbo mufflers on my Willys with a header to bumper set of 3 inch pipes. It's far too loud for what you want. If it had some kind of resonators it would be ok I think. You may be able to get some replacement mufflers say from a 396 Chevelle from Walker of other mfg that would be very good. You could add resonators if needed after the install. Why not just use the 409 mufflers.?? You can get them in 2 1/2 in pipes I think.