Here is a list of the modifications I’ve performed to my Boxster to make it a little more personalized and user friendly.

• Rolling top up/down relay modification
• Clear side markers
  
• OBC (onboard computer) modification to display outside temp, fuel economy, etc. Link 1 Link 2
• European drivers side wide angle aspheric mirror
• Silver crest valve stem covers - $12 from Porsche
  
• Bumper Plugs for the front plate location to match bumper
• Audio system
• B&M Short throw shifter - Buy Install
• Foot well lighting: Link 1 Link 2
• Removed Airbag Stickers on visors using denatured alcohol
• Removed Intake Snorkel to change induction sounds and perhaps slightly increase horsepower
• Ultimate Cup Holder installed on drivers side - out of the way and works well!
  
• Clear (2003-style) front head lights w/ Amber diffuser filter removed, Philips Silver Vision PY21W (1156) turn signal Bulbs installed
  (before / after picture of internal amber diffuser filter removal)
• Clear (2003-style) rear tail lights
  • Philips Silver Vision PY21W (1156) turn signal Bulbs - silver bulbs that illuminate in amber to replace standard amber bulbs in the front and rear light assemblies. I purchased from AMBulbs.com. (The bluish Sylvania Osram PY21W Diadem bulbs are a second choice.) You may have to break off one of the tabs at the base of the bulb to insert it into the socket.
• Wheel spacers: 15mm front and rear. (Wish I’d gotten 17mm rear, in case ever I decided to install wider 911 rims.) I’d considered 7mm for the front spacers, but that would have been too little of a difference vs. stock.

Potential future upgrades (most likely at the top):

• M030 Sport Suspension Upgrade
• Replacement soft top with glass rear window - Link
• Zeintop Cayman-style hardtop - Link
• Flashing side markers with turn signals - Link
• Variable intermittent wipers - Link
• 3.4L or 3.6L 911 engine upgrade
• Painted center wheel caps - Link

Track Accessories:

Magnetic Numbers for doors: 8″ tall, Black on white rounded rectangle background, Gill Sans font. I purchased these from FireBallGraphix. (The number on my car: 808.)

Head Protection: I purchased these from Summit Racing.

• G-Force Pro Force One full face helmet: black, Snell SA2005 rating. I like the reasonable pricing of G-force helmets, their lighter weight due to a composite shell, and the fact that they have HANS (head and neck support) attachments.
• G-Force Pro Fit Smoke shield. The shield is easy to swap-out and the smoke shield can be used on sunny days. Still, no shield and sunglasses is more comfortable (because that is somewhat cooler).
• G-Force helmet bag in black.

Related links:

Boxster Hacks - a collection of tips to make your Boxster a little more user-friendly
Sunset Porsche - Sunset Porsche in Beaverton, OR. Bob McCarty is the parts manager. The best place to buy Porsche parts I’ve found. 1-800-346-0182.
Porsche Pete’s Boxster Board - a great place to casually discuss everything Boxster
RennTech.org Forum - threads are more persistent in this forum so it is better for technical/mod discussions
Babblers Board - another great discussion forum, especially for those on the west coast.
Porsche TechArt - aftermarket equipment from Porsche
Bumper Plugs - Match your paint color, hide the ugly mounting for front plates.
Hack list - a list of common modifications from the Boxster Board.
Titan Motorsports - The place to buy a B&M short throw shifter
B&M Shifter Install Notes - Some notes from those who have performed the upgrade.
Foot well lighting - Wiring instructions. Also includes spoiler instructions.
Henry Verheyen’s Boxster page
Mike Frocke’s list of salvage companies that specialize in Porsche parts