Yep. Listen to mell0.
Get a either the Diablo Predator or the SCT. I have the Predator, because that is what the shop that tunes my car uses. I bought it for my first mods (CAI, Borla catback, 4.10 gears). My car is an auto and it woke up big time. Being able to change the shift firmness and the shift points made a big difference. Also fixed the speedo, which of course has to be fixed after a gear change. After that, it was used for the next mods (custom tune for Kenne Bell 2.1L 9# SC intercooled kit, MRT H pipe, went with 3.73 gears). I use it as a scanner (to read and clear trouble codes), I probably will have to use it if I go with 18" rims.
So go get a handheld tuner. You will use it...
2002 GT Zinc Yellow Premium Edition, Borla Stinger Catback, MRT Catted H, KB 2.1L 9#, Accufab 70mm TB, FRPP 3.73 gears, SCT custom tune, street/strip valve body, Mach 1 Grille Delete/Chin Spoiler/Brake Upgrade, Bullit suspension kit, Steeda UCA/LCA