The difference is engineering. Borla engineers the system for the setup. The Magnaflow is just a "muffler." Not designed for a specific application. Borla's will probably include a resinator to keep the back pressure. I have "Borla" system which I got on ebay, which Borla says they didn't make, says Borla on all the parts, maybe it was made for an SLk320, fits perfect and it sounds and works fine to me. A little louder than stock, deeper tone, but I can still talk a 60-90. And I supose it does sound a little like a ricer, but what can you do - you get a "metalic whine from the engine at high RPM which is noticable when standing behind the car. Can't hear it in the car and don't know what is sounds like from a distance. I made a video with my Digital camcorder, Unfortunately don't have a web site to post it on. Anbody who wants it I'll email it to you - its about six megs.