Legalities aside, it still probably has better stopping power than your average commo on the streets, so if you're just driving sensibly there isn't an issue. You just have to adjust your braking style to compensate for the power of your brakes (ie: brake a bit earlier and be a bit more aware of your surroundings). The only danger really is if you're being a twat.
Sure, researching helps, but everyone starts the learning process somewhere, and could have done worse.
On the legal side, I can't comment about other states, but in WA, so long as the car's neat and looks pretty well stock, if you have the right attitude to a cop, they aren't going to know that it's not a factory turbo, they'll just think it's a GTST.