For the good stuff...
Follow the links below for more web pages containing all kinds of hopefully useful info. Most of the component related links are from products I have personally used.
Clarion - Real Audiophile Audio Shit.
Kenwood - Audio Shit.
Uniden - BearTracker scanner, CB radios.
GTech Pro - Measure vehicle performance.
Valentine Research - The BEST radar detector.
Radar Guys - Follow Uniden link to BCT7.
Susquehanna Motorsports - Hella H4 lamps for cheapest around.
K&N Air Filters - More air = more HP
Borla Exhausts - Relieve back pressure.
Unorthodox Underdrive Pulley - More power.
Magnecor Plug Wires - Low resistance wires.
Hotshot Cold Air/Headers - Freer breathing, an awesome but complicated mod(headers).
Eibach springs - Better handling.
SP Motorsports - Lots of Probe stuff.
Island Motorsports - Closest place to home.
R&E Racing - Cheapest place to order Borla exhausts from ($346 for the PGT cat-back).
Hella Headlights - Let there be light!
Stern Lighting - All you ever need to know about headlamps, including some how-tos.
Ford Probe FAQ - A great "starter" page about Probes, but a bit under-updated lately.
Julian Bradbury - The best Probe maintenance page around. Repairs, preventative care, maintenance.
William Chenoweth - aka Ntruder. Posted the highest numbers for a naturally aspirated PGT with his fairly unique setup. Partner-in-crime with Dan on the Turbo project.
Dan Dunhem - WAS NOS powered, but soon to be turbocharged. William's partner-in-crime. One of the most killer sound systems. Also one of the most powerful normally aspirate GTs.
Justin Fuller - One of the most complete parts listings around.
Jason Hunziker - A very well designed and frequently updated page I've jacked artwork from in the past. Sorry, Jay. :)
Ross Lapkoff - NOS powered. One of the best pages, bar none. Car mod how-tos, dyno runs, racing tips, club information, etc.