Find a very good shop to install
Out of the box, the Magnaflow for my STI had so little clearance that I came very close to sending it back. And that would have been a huge hassle. Fortunately, my installer was Cobb Tuning. The guys there went way out of their way to "make it fit". Lots of benchwork - hammering on heat shields, etc. - to acquire clearance. So far, no rattles or contact. But I will be taking it back to Cobb in a week to check the fitment again. Looks great. Sounds great. A very poor fit from an otherwise good company.
I have always heard good things about borla systems and decided to give it a try on my WRX. I couldnt be happier!! It sounds absolutely phenoninal and intsallation only took me 10 minutes. Everything just fit perfectly. It took me more time to take the stock exhaust off than it did to assemble and install the new one. If your a real car enthusiast and want quality for your money there really is no other way to go.