Underbody Exhaust Help...ERA 427 Street

[DanEC]

ERAs have aluminum floor pans so it's not quite as difficult for us. I coated mine with several coats of ceramic based Lizard Skin on the underside. And then on the top side I used a thin mastic damper-proofing and a double sided insulation layer by EZ Cool. With fiberglass floors I think I would apply something like the Lizard Skin material but also use a metal or aluminum heat shield between the muffler and floor. I'm also ceramic coating my head pipes and mufflers which I hope will knock a few degrees off of their external temperature when the car is running.

[427 Street]

Originally Posted by DanEC

ERAs have aluminum floor pans so it's not quite as difficult for us. I coated mine with several coats of ceramic based Lizard Skin on the underside. And then on the top side I used a thin mastic damper-proofing and a double sided insulation layer by EZ Cool. With fiberglass floors I think I would apply something like the Lizard Skin material but also use a metal or aluminum heat shield between the muffler and floor. I'm also ceramic coating my head pipes and mufflers which I hope will knock a few degrees off of their external temperature when the car is running.

Good tips.

Doug at ERA is the tech guru and he said that the stock mufflers are resonators from a '79 Trans-Am....when he said that, a bit of my breakfast came up . He said that they are a 14" body in length (not including the inlet/outlet), and that they are 3.75" thick. They are an offset inlet and a center outlet...2" in and 2" out.

He also said that most tubular glass-packs are 4" in diameter, so 1/4" should not make a huge difference. He also said that he is "pretty sure" I could fit a 24" muffler under the car.

I am really tempted to try try the Chambered Classic muffler after speaking with Eric. It seems like it is the best of both worlds for tone and volume. Eric is an engineer who worked at Dynomax for over 12 years, and I think he developed five of their current mufflers. He said that SIDE pipes are very restricting to flow, too loud for the street, and real HP suckers, but he started his company to change all of that.

So my underbody exhaust questions to all of you: What mufflers have people tried? What works? And what have you been happy with and sounds amazing?

[DanEC]

A 24 inch muffler would have to hang entirely below the chassis outriggers. My mufflers suck up between the outriggers in the pocket they form. Only the 2-1/2 inch pipes have to clear the outriggers. (See Bob's note above about the pocket measuring 19.25 inch). So I'm not sure I understand what Doug is saying about a 24 inch muffler fitting. That would put the mufflers about 1-1/4 inches lower than my mufflers at least. That is going to be hanging down pretty low.