Hey you, guys a little less negativity now!!
First: Make sure your car is running in tip-top shape.
This includes changing the plugs, wires, pcv valve, o2 sensor, air filter (k&n), updated knock sensor, and anything mechanical that needs replaced: half-shafts, wheel bearings, hood latch...
Second: Actually still part of the first, but get the inside of the engine cleaned up. How you say? Search for "Sea Foam" and "Water ingestion". And part of this includes an Italian tune-up. Get on the highway and beat the wizz out of the motor to get everything nice and hot to break up that nasty carbon.
Third: Free up some back pressure. Since it is N/A, merely replace your muffler with a free flowing unit. Your choice of muffler. I like glasspacks for a cheap zero backpressure muffler. Should be quiet until you get on it. The stock piping will provide enough velocity for the exhaust gasses, the muffler only restricts the flow for the sake of super low noise.
Fourth: Get weight out of your car. The horsepower to weight ratio is what determines how fast a car can be. That's why a Lotus can kick butt with a mere 197 hp and run like a V8. Weight reduction will make the biggest difference.
And get skinny tires pumped up with a lot of air, less rolling resistance for straightline speed - but that's optional.