Errr. My opinion is N/A 4AG. 16v or 20v. Throttle response is amazing, its a lot of fun, and still can pull of some serious stuff. Anyway, boost takes away the character a built N/A 4AG has. I dunno man, just my opinion. If you need a little more power, do mild engine mods. Like my car has intake, header, test pipe, 0.5 mm head gasket. Those little things have made my car powerful enough for my taste, at least for now.
And just a thought, I'd rather get a cage so you can do tandems than build more power. Also, look for more ways to lower the weight of the car (I know your car is already lighter than mine), because not only will your power to weight ratio go up, but you can turn and stop faster, something HP can't do.