Hey dude, It actually depends on what you are looking for in performance as to which system you want. The cold air system works by letting the motor intake air more easily and of course keeping the air charge a bit cooler than the stock setup. The cold air system adds a little more power all the way around. The ram air system only really works when the car is moving. Off the line acceleration isn't quite so good as the cold air system but, once at speed the pressurized cold air has quite a good turbo affect. In this case the faster you are going the more power you can make. I haven't heard too much about the acceleration benefits of the cold air systems but, I do know that the ram air system can take at least a tenth off your quarter mile times. Good luck