First off, if I change the size of my pulley do I have to add another fuel injector? Also, what size pulley would be best for my car (s/c 01')?

What pulley size are you planning to upgrade to?

That's one of the things I'm wondering. What size would be best for just a few more psi of boost?

how much more boost do you want and what pulley do you have now? 3.125 is a pretty good pulley that gives you a quick response and good peak boost (~11psi). smaller pulley will require modification on to the mounting plate.

you dont need an additional injectors, you can always use a high ratio FMU to raise fuel pressure for more fuel delivery. additional injector requires a lot of tunning and you cant gaurantee that each cylinder receives the same amount of "additioanl fuel".

I would get a new disc for your FMU. what FMU ratio are you running now? I had 8:1 for my 2.87 pulley @ 10psi and I was running rich.

Here's a chart Iansw posted regarding pulleys and their respective boost:

http://www.nwmaxima.com/viewtopic.php?t=1669

Where did you get the info on the sizes of the belts and pulleys from? Also, if I went to 9 psi from 7 would I need to do anything elso to my engine, or would it be alright?

do you know what FMU ratio are you running? if you have 6:1, you might want to upgrade to 8:1.

you might have to grind the mounting plate a little for the belt to pass.