I received my Moroso spiral muffler Thursday.
I have mixed test results, but I am more than happy with it for my needs!
When you look inside the muffler it looks like a one-piece auger plate welded around about a 2" straight through pipe. Simple, and sweet. Plus it wont blow out like a glass-pack muffler.
My first test was to just push the body of the new muffler into the tip of my existing ATR glass pack muffler. The noise level dropped tremendously!
I've had a dual 2.5" Road Race muffler tip for about 2 years now, so I went ahead and made the switch. With the ATR system being entirely made out of stainless steel the old muffler slid right off. The new muffler is nearly a perfect length to be used with the Road Race dual tip to fit nicely. I had to do some custom cutting and bending on the dual tip to have the exit point out correctly. The new muffler mounted with the existing muffler clamp just fine and I temporarily wired the slip on tip to the rear hanger. I will get it welded on with a hanger bracket at Josh's this Saturday.
Before I started the install I had Carmen take a sound bit/movie on her phone from about 6 ft. behind the muffler. After the new muffler was installed we did the same thing. I don't think they are worth posting because when you compare the sound bits, the new muffler sounds louder and that is most certainly NOT the case.
The new muffler doesn't sound as quiet by it's self as it did when pushed into the ATR tip, but it has knocked down just a TON of resonance. Inside the car is where I hear most of the difference. Since it does seem so much quieter, I took it out for a spin to make sure the performance wasn't cut down too much. WOW, it must be the fact that the exhaust isn't as loud from the rear that makes the power seem to be more of a surprise on your senses. If there is any power loss, it is small enough that I can not feel it by the seat of my pants.
It aint your grandmas Buick, but I can hear the radio now without blaring it and the interior is not rattling as bad with so much less resonance. Plus it still hauls the mail!