ERA's stainless steel pipes are made by Stainless Specialties (
Stainless Specialties - Home). I have SS pipes on mine which has been on the road since 2003. My car has always been loud but over the years it seemed to get louder. I've spent a lot of time with a lot of different Cobras and mine was always the loudest of the group.
Well, I finally got tired of always having to wear earplugs for fear of blowing out an eardrum if I didn't so I contacted Stainless Specialties to see what they could do to quiet my pipes down. I put a bore scope down my pipes and discovered that I likely had a 20 inch muffler (even though the actual perforated section was only about 14 inches long) with very few perforations between the inner and outer chambers. From what I could see with a bore scope, there was no insulation whatsoever between the chambers.
In speaking with Stainless Specialties, they told me all the pipes they sold to ERA since at least 2000 or so should have insulation between the chambers. In any case, they told me they could change out my 20 inch mufflers for 28 inch ceramic packed mufflers. They could go with either a 3" diameter chamber or a 2-1/2" diameter chamber but that since I was interested in quieting the car down, they recommended the 2-1/2".
I chose the go with the 2-1/2 inch. I took my pipes off, shipped them back and they swapped them out and returned them to me within about 2 weeks or so. They charged me $660 plus shipping. After getting the new pipes back, I took a look with my bore scope again and discovered that there was a huge difference in the number of perforated holes between the inner and outer chambers. I would estimate that the new mufflers had at least 5-10 times more perforations.
I couldn't be happier with how the car sounds. It does still set off alarms and everyone says it sounds great, but now I can cruise around town without earplugs (although I still wear them on the highway). Best of all the local cop no longer pulls me over and threatens to ticket me.
As far as performance, I haven't done a before and after dyno test, but I can't tell the difference in performance.
I'd do it again in a heartbeat.
Chris