I just installed these last weekend and I have a few miles on them, enough to render a verdict, which won't be a surprise if you read the thread title. So I'm running these behind the Magnum 5.9 (stock cam), Doug's headers, 2.5" pipes, no crossover. These are 18" long, 9" wide, 4" thick, offset on both sides. They fit really well fore of the axle and have exactly the same dimensions as the "stock style" cheap sheet metal mufflers that they're replacing. The good stuff: pretty cheap. They can be had for $35-$45ish depending on the size, model. They're supposed to be comparable to Magnaflow (similar design) but I'm just taking the internet's word for this. The welds all look nice, etc. Not so good stuff: First, they're surprisingly quiet. No, I don't want a huge amount of noise but I'd prefer if they were a notch or two (or three) louder...my wife said that she could barely tell the difference when we were driving around! That doesn't seem right. The more concerning part is that they sound "off." There is a bit more noise (over stock) from outside of the car but also a slightly displeasing quality to the sound that I can't quite identify. Under full throttle, near the higher end of the rev range (this is a Magnum so read that accordingly) they develop a "thudding" quality that just doesn't seem right to me. It's enough of a resonance to make the rear view mirror vibrate. What are your thoughts? Other folks have been happy with them. I'm wondering if I could have gotten a bad one. It's such a simple design that I just can't imagine how they could screw that up.