I HATE the chambered Flowmasters. I have the 50 series, three chamber on my 318 Valiant and it is a sonic warfare device between 1,900 and 2,600 RPM. The resonance is so intense it affects me more than annoying, it disrupts my ability to function (normal). I have a Turbo 2.3 in my Pinto, there I have a Dynomax that was a replacement in the T-Bird Turbo Coupe donor car. Pretty quiet muffler. Sorry, don't know the model number but I'm not a big spender so I assume it was a general, universal part. Here is a picture of the box..., and my daughter. She's 22 now. So is the muffler.