This has been discussed a million times. I don't think there is any noticeable performance differences. Ultimately, price and availability are the deciding factors for most. The Banks is a bit more expensive but you get a more complete kit - exhaust, pyro and boost gauge. With the ATS, you get nothing other than the turbo and filter assembly. Bank customer service is top notch - I don't know about ATS. The ATS system looks almost factory when installed. That's probably because they are the one who built the system that went into the the factory turbo'd IDIs. You will see 9-11 lbs of boost, depending on your fuel setting, with either system. I regularly see 10.5 at WOT. I've heard no negative feedback with either system. Good luck with your search - you will be happy with either one.