The real power boosts are usually obtained by a combination of methods, rather than a single cheap ebay scam.
For the best budget results could I suggest:
1) Windscreen washer LEDS
2) power resister from the Bay
3) drive with your front fog lights on during the day
4) a magic tree (ocean mist, or bouquet for the greatest gains)
5) a random shopping list of things you'd like in the car, but in reality you don't have
6) Excessively loud music via cheap 6*9s is sure not only to increase top-end speed, but will also win the admiration of the general public as well. Even more i you share it by driving with all your windows down
7) Smaller gains can be made by wearing caps at a silly angle and also reclining the driver's seat so far back that you have to lean forward to reach the steering wheel. Although the cripple hook gives marginally better results.
V.