I'm running a full 3" exhaust pipe made out of Ally. I used to run a straight through perforated ally muffler I purchased from Summit Racing for $90 but I blew all the stuffing out on my third event. The car sounded great and the entire exhaust was so light.
After that I switched to a SS muffler and after five events that one broke all the internal welds inside and the end plates started rattling around. I have just installed a magnaflow now which so far is holding up fine and looks better made than the previous one so hopefully it will last.
My exhaust pulses at idle are extremely violent, if you hold your hand near the exhaust outlet it feels as though someone is slapping your hand and it actually stings. I think this combined with the exhaust temp destroys mufflers.
I'm thinking of making my own ally muffler, with steel wool packing around the perforations then rock wool outside. I think it would be fine then.
Someone else needs to try the Vibrant muffler from Summit and report back if it's ok. I think on a more stock MX5 it would be fine.
The last 24" of my exhaust is aluminum tubing, replacing a straight-through muffler that I used to have there in the interest of saving weight.
Exhaust spits flames on the track and the aluminum is still holding up so chalk one up for the aluminum. But, do note that it expands and contacts severely during a heat cycle, even for a straight section of tubing. I could see an aluminum muffler cracking in a short time.
I've been using the vibrant with no issues so far, only been a few months though and only used at the extreme rear.
Yeah mine was at the end. The vibrant muffles seem well made. I didn't think there would be enough force in the exhaust to destroy a muffler when it has a clear 3" pathway for the air. The packing got blasted out at the back inner weld in one puff as I was reving the engine prior to launch.
Awesome!! Can't believe I got this much of a buzz in a short period of time. Anyone have any sound bites? I'm looking to do strait (currently in place) to the rear axle then alunimun to the vibrant aluminum muffler. I'm n/a so it will be mega loud? I run a shitty $25 walker muffler but now I've had to reweld it 3 times i'm over it.