aem is great if you have the money for it, and if you can find someone to teach you how to program it and what those adjustments will do. Ok you don't have to know how the aem can be programmed but I like to know whats going on with my car.
also if your staying with a standard turbo setup running less than 20psi and your using the car for street driving and a weekend track start then aem is a bit overkill. but if your car is drag only, and you have gone so far as to rip every bit of the interior out, and your running 30+psi then you may want to look into aem.

If your running on the street DO NOT run an open downpipe, with a honda and alteezas your already asking the cops to profile you as a street racer and are just giving them another excuse to pull you over. ditch the cat, if you want to keep the dual exhaust then look into partially removing the internals of each muffler so that you can lower back pressure but still keep the system as quiet as possible.