Stainless Specialties in Sebastian FL:
http://www.stainless-specialties.com/
They do pipes for Cobras. They have two types: baffled and flow-thru. The flow-thru are like glass-packs but he uses what he calls a "ceramic mat" material instead of fiberglass. Either way, they're guaranteed for life. I had a fellow ERA owner in New York send me some info on his ERA. He originally had the baffled ones which he says showed a power loss of about 45 hp on the dyno as compared with straight pipes. He switched to the flow-thru and said he got the power back along with the noise. It's a trade. I had the flow-thru on my car and they are loud.
One word of advice. The Shelby/ERA style use a slip-fit between the header pipes and the sidepipes. These are notorious for leaking, which results in backfiring on deceleration. The flanged types are much better if they will fit on your car. Stainless Specialties will make either type for you. Hope this helps.