Probably only an answer that you can provide. Is $300 worth it to you for temporary satisfaction? Or, can you hold your urge off long enough to wait for the pulley? You know the $300 will be a loss once you put the pulley on. So, IMO, I would apply the 300 to the cost of a pulley and wait on the tune. Heck, you are well on your way to a C3 with that $300. To be honest, you will probably feel more of a butt dyno change by adding the pulley than you will with the tune. The tune does tie it all together, but I had instant satisfaction when I added the C3..... You could not wipe the smile off my face. It is kind of similar to the change that you experienced going from stock to the NW CAI. It was like driving a completely new car.

So, long story short...... IMHO, I would get the pulley first. Enjoy the performance gain that the pulley will provide, and then and only then put the finishing touch on it with a tune. You already know this. Maybe it helps to hear someone else say it though. Good luck, and happy modding.