Well, I should probably change my signature to reflect what my car has done to it. Anyway, I added the Sprint Booster first and loved the new throttle response. We all know this does not add any horsepower. All it does is take out the non linear curve of the throttle mapping and make it linear. Does it feel quicker? Yes. Is it Quicker? Only in reponse. Do I love it? Yes. Does the tune do the same thing? To be honest I do not know. That is a question for the tuner.

Second add was a Eurocharge power tune. Does this add horsepower? Yes. In my opinion having both the tune and the Sprint is the ideal combo. I don't feel I need anything else done. Oh, and I also have the second generation booster that has three settings. Off, medium and race. Medium is perfect. Race is too abrupt and makes the car jerky. Since I bought it I have never taken it out of medium.

So as someone that has both the tune and the booster I like them both. If you only have $300 to play with I would still do the booster first.
More bang for the buck. Again, this is only one mans opinion.