im rite there with ya... theres an 04 gp gtp thas already mine i jus gotta pick it up on tuesday im so stoked!
Welcome aboard.
My first modding suggestion would be intake and custom tuned PCM. Not too expensive, and you will love the PCM.
I'm lovin every minute of it. Even stock, it's a lot of fun to open it up. I traded in an 03 Kia spectra with 3 of the 4 cylinders misfiring, and the exhaust 60% blocked by metal shavings from the engine basically destroying itself.... so you can imagine the difference haha.