the tune brings it all together...if you put a pulley on and no tune, it will run great, maybe too great, meaning you may or may not be leaning out at the top of the rpm's. All the tune does is bring everything all together within safe parameters, and does help with a little HP as well. Until you get your boost up, you are just wasting time and money getting a tune. It is tough, I know...I had to pass on a tune, because I didn't have everything on as well, but the tune is the very last thing you do....good luck..