These stick on vents are the best bang for the buck. DIY is simple and straightforward. Peel the tape back and slap it on under the 86 piston. You get about +100hp PER addition, this means you can get +100 hp to your rear right wheel and another +100hp to your rear left wheel if you decide to put one on each end. Be careful if you only put one on. That side will be pushing twice as much power as the other wheel.
On a more serious note, if you bought this car for HP, I think you got the wrong car. There are definitely many more cars that are better for the $ if you care for HP+Drifting.