Getting started on 02 GTP

Hey i just bought a 02 GTP i was wondering what i should upgrade or do first i was thinking either starting out with a full exhaust Cat and all but i dont know a good brand Or i was thinking just upgrade the supercharger pulley to a 3.4 i need help on what i should do to get my car ready for a 3.4 mm pulley and all and what kind of an intake is good for this type of car iv been looking around and havent found much for a good price i want this car to run good so i need help on things like upgrading the pulley so i wont mess my car up when i do it and what is best for the car when first starting the work on it

Welcome to AF!!

The first thing to do is to put on a cold air intake. Then upgrade the exhaust. The stock exhaust flows well but removal of the u-bend will make a huge difference. You can purchase the replacement part from various stores including PFYC, ZZPerformance and etc. As for the 3.4 pulley do the upgrades to the intake and exhaust first. If you want a cat back exhaust there are several, Borla, Flowmaster, SLP and even GM Performance parts sells one.