The following modifications were done to it:
B&B final muffler
Factory rear deck with doors replaced the small jump seats *
ROW 030 springs *
ROW 030 larger sway bars *
Brey & Krause strut brace
Turbo S air inlet replaced standard fog lights *
Carrera RS front splitters *
Carrera RS rocker panels *
Carrera RS rear spoiler *
Carrera RS center caps *
Carrera RS logo on rear deck *
Kinesis super cup wheels
Power flow intake kit
Turbo 11.7 rotors and calipers [black] front and rear *
[Brakes were installed after photos were taken]
Cryogenic treated rotors
Stainless steel brake lines 
*Factory Porsche parts

I liked the looks of the Carrera RS because it was not outrageous, but it complimented the lines of the car.
The chassis modifications tweaked the performance of the car so that it handles very well on the track at driver education events yet still is a comfortable touring car.  The exhaust and power flow modifications allow the car to breathes better and are fun to listen to.  I credit the factory Porsche springs for lowering the car without causing problems on most steep hills.
The engine is stock except as noted.  There may be some changes in the future to the engine but the cost to increase the horsepower seems to be too expensive for the return on investment.  It seems just fine for now.

This is my fifth Porsche.  My past Porsches were: ’68 912, ’89 944, ’93 RS America and a ’97 Boxster.
The 993 is a great automobile and I am not yet tempted by the 996.