So I'm at a crossroads, I'll see what the masses think. I have a relatively stock 2004 GT, I'm stuck between two kits to purchase from RPM outlet (please don't bash RPM outlet, that's not what this thread is for). On the one hand, there's the tuner and underdrive pulley kit, $450, which I could install right now, gain a few ponies and be happy. On the other hand, they have a tuner and gears (with bearing kit) option, again $450, but I am hesitant to purchase this kit as I would much like to have a new differential when installing new gears. So what do you all think? Do you think I need a new diff, would it benefit me to hold off until I have a new diff to get gears (I'm not sure how much easier the install is if I have both pieces at the same time). Or should I get the UD pulleys which I can slap on right now? Opinions on potential gains? Pros and Cons of either? Whatever you all want to say.