welcome to the forums, good to see you are taking care of the car. here is a good place to start when it come to modding your engine, supporting mods are key for these cars
http://www.grandprixforums.net/f81/s...car-17482.html
as for my opinions, here goes:
-msd wires are good and keep stock coils
-do autolite 104's because GTPs love copper plugs
-180 or 160 deg thermostat is totally your choice
-defnatley by headers and they come with their own downpipe. changing the rest of the exhaust will not net you anymore HP it will change the sound only. be sure to keep some kind of resonator in there or it will be rraassppyy
-having your throttle body, s/c, and heads ported is an excellent idea if you have the money
-throttle body spacers are a waste of money, no gain there and deleting the a/c pulley is also up to you as i hope your summers are not hot and muggy like ohio's
-a cold air intake is good because colder air combusts better but you wont get as good of gas milage and short ram or open cone intakes are for better gas mileage and better flow, its al in preference
-just keep new belts on (not 100% on brands) and you will be good
-a new water pump is a good idea and not sure about high vol oil pump (just dnt know that much about them)
-for the cam, springs, and retainers, search the forums for what other members say or maybe someone will chime in
-with a good tune a 3.25 inch pulley souldnt be a problem
-a street tune (HP tuners) is your best bet but a mail order tuned PCM by DHP (sold by 3800 performance) is the best to buy
hope this helps!!
