Spend it now, but don't put it on. You have additional work you need to do first, and should own a scantool or have access to one before you get the pulley. You need to know if you have any KR first, and after. You should also have a good CAI or FWI, 180° thermostat, and possibly PEM'* first. A custom PCM wouldn't hurt to take full advantage of it.
A pulley isn't a magic solution. There'* other work involved before each step down.
Out of curiosity, is this a private seller, or a retailer?