Welcome!
Here is the advise I have been giving the newbies:
"Right after I got my P5, I got the intake. You have the short ram intake (SRI), which is what I have. Others have cold air intakes (CAI) They are about the same on ebay, but you may also opt for name brand. I have the ebay...
The next thing I did was get rid of those god forsaken Dunflop piece of s*** stock tires. I hydroplaned within the first week or so I owned the P5. I ended up with the Yokohama AVS ES 100's. 205-50-16's on the stock rims. There are a bazillion threads about tires. These I highly recommend for rainy climates. (Bottom line, get out of the stock tires before you have a problem!)
I just got (after 2.5 years of owning my car) a Racing Beat exhaust. I got an insanely good deal on it. It is on the higher end of the pricing range, but you can score one used at a good rate if you are on the forum within the .245 seconds someone posts it for sale used. They run in the high $400 range new. There is a Mazda Sport (Mazdaspeed) exhaust which is also popular, but people have complained of droning, or an annoying sound at freeway speeds. The Racing Beat does not do that. But there are a bazillion threads about the exhaust subject too, look them up.
Then there is the tinting of windows, a stereo, springs/shocks/body kit, carbon fiber everything, etc you will see around here for sale.
Short shifter is next on my list. Kartboy makes a great one, I have seen it in person. The shifter bushings are a must. Get them no matter what.
www.protegegarage.com has a B&M for only $79 and shipping right now! TWM also has a short shifter with a discount code here:
http://www.msprotege.com/forum/showthread.php?p=1639737#post1639737
One more thing you should consider when you mod is a header. OBX and Ractive are the most common. I just installed the Ractive, and love the HP gains.
Well, good luck, and check out the for sale section, and work with the Authorized Venders and sellers! Oh, search for threads about a question you might have. Most likely, it has been covered."