I'm simply saying that a generalized correlation seen among modified Subaru turbos- that a 3" catback mated to a good 2.5" catback or axleback is closer in performance to a full 3" than full 2.5"- is true, but it has been falsely attributed to the Ideal Gas Law, and to the idea that the exhaust flows better downstream because it is cooler. If you're ever around a dyno operator who is silly enough to let non-employees close enough, stick your hand right behind the tailpipe during a full boost, full throttle run and tell me that the exhaust has cooled down all that much. Or just look at my rear bumper sometime.
