The first step, as always, is uncork the exhaust... in accordance with Federal, State, and local ordinances, of course. Fast Intentions seems to be a very popular brand here. It will also be of vital importance to bring the car current with ALL maintenance checklist items; chiefly fluids.
Then, add a little boost and see what you think. I'm currently playing with a Z1 HotBox and JB4 (not at the same time) to see what these simple, fun, electronic toys can do. These are plug & play controllers that adjust the boost from the turbos to increase engine output.
The Z1 HotBox adds a little boost that you can feel, but is safe for the engine. Its adjustability and capability are pretty limited though. It seems to be aimed at those who want a bump in power but are not familiar with all the technical details required to get there. Mine is up for grabs; PM me if your interested.
The JB4 is much more sophisticated, flexible, and can be more involved. It can also be installed and set to one of the precongigured settings without having to understand all the ins and outs. However, it can also be played with and turned up by the uninitiated to the detriment of the engine, so beware.
You did not mention whether your car is a Red Sport. If not, you are starting out with 300hp; and you should be able to realize impressive gains without too much trouble.