I have a 3" system with x-pipe on my 440 cuda. It was tight getting the motor in from the bottom. I had to loosen the passenger header, set the k-frame, and then retighten the header. Drivers side was fine. The x-pipe clears my 4l60e auto trans without a problem. I have no clearance issues over the axle. My chassis was originally a small block with single exhaust. I had to source another hanger mount on the drivers side infront of the axle. That just tack welds into place. I thought I was going to save a few bucks and use somebody else's exhaust tips that were cheaper. They won't fit. You have to use TTi's exhaust tips. They look alright and fit nice. My system fits nice. I did have to hammer some clearance at the idler arm so the zerk wouldn't rub. I also had to clearance the drivers side where it comes too close to my oversized torsion bar so the motor can move a little bit. No issues in the past couple thousand miles. I re-torqued the manifold to head bolts after a few heat cycles. I also re-torqued the collector bolts after some heat cycles to prevent future leaks. No leaks, no rattles, and no issues at this point. They are very solid and kind of heavy. I can't imagine this system will save you any weight over a stock system. Even with cast manifolds. As far as mufflers go, I got the longest ones that I could get from TTi so they wouldn't be too loud with the 3" pipes. I love the sound of mine. Not too loud for cruising. Not too loud when I mash then pedal, but still sounds pretty "healthy". You can hear the air moving easily through these pipes.