Here's my 996 cabriolet with the hardtop on, with my 944 turbo (track car) in the background.  Minimal mods, just some exterior and interior cosmetic changes.  On the exterior, I have a GT3 front bumper cover and side skirts, and a Strosek Level I rear spoiler.  On the interior, I have aluminum brake pedals, gauge trim rings, white face gauges, and deluxe color crest shifter.  The stereo has been slightly upgraded to include MB Quarts in the cabin and an Infinity Basslink in the front trunk.  I kept the factory CD head unit for aesthetics and added the auxiliary input connector so I have my iPod plugged in!

My first track day, Laguna Seca, with the top down! (David Wong photography)

You can see how nicely the Strosek rear spoiler complements the lines.  I selected the Strosek rear spoiler over the factory GT3 aerokit rear spoiler because I wanted a rear wing that looked like a natural evolution of the 80's and 90's 911 whale tails.

At Laguna Seca.  I took both of my cars to this track day, running the 944 turbo as my primary track car, and had the 996 as a backup.  On this particular day, the 944 turbo blew a head gasket on my 3rd run.  I decided not to push my luck and didn't run my 996 the rest of the day. 

Cockpit view!

My shifter upgrade.  This is a super classy upgrade for the interior of a 996.  If you have a 996 with manual transmission and you don't get around to changing anything else, change the shifter!  The standard factory shifter is plain, unattractive, etc. - this OEM option shifter is what should have come on all 996's.