110% agreed, dont waste your time and money
do what 99.9% of everyone else does, and that is to go and get your car tuned, by a professional, to take in account every nuance of your own particular cars features and limitations
it'll be safer (for your engine), more powerful, and better for the environment (and your long term petrol costs)
If you're up north, road and track dyno, morpowa, willall and horsepower in a box are available
if you're down south, southern hitech dyno, turbotune, graham west can all do the same job
I prefer road and track and southern hitech cause I know both of the guys there but call around and see which one can fit your expectations the best
-D