First things first. My car is a 1998, 6-speed, convertible, Z-51 suspension. The C5 has a terribly restricted air intake. This was the first place I started to improve performance. I first had the usual open K&N filter, but have since upgraded to the "Breathless Performance" ram air system. This picks up air from the bottom of the car at the high pressure area which feeds air to the radiator. The kit reguires cutting the shroud, but it is not difficult. I strongly recommend removing the shroud to cut it, trying to work with it mounted in the car is very difficult. This mod is a major benefit to the C5. Pics of the installed system are on the photo page.I have also added HRE wheels from Mallett. These wheels are wider than stock with the correct offset to allow mounting 275 40 17 tires on front, and 315 35 17 tires on the rear. I do not use run flat tires. I keep a mini electric pump in the trunk. So far (knock on wood) I have not had a flat. (The original wheels/tires were still in place for the photo on this page).
I also added B&B mufflers. The sound is a very good compromise between sporty and quiet, and I prefer the squared tips to all others I have seen.
Other mods: by-pass solenoid for the 1 to 4 skip shift; screen removed from mass airflow sensor; throttle body coolant bypass; relocated air temp sensor; adjustable fuel pressure regulator; Beru non-resister spark plugs; Nology capacitive ignition.
My thanks to Ron Bilyeu of Pro Auto Tech for the fuel pressure set-up at Bowling Green during the labor day weekend.
The car runs strong and smooth, and in nearly 3 years time has given NO trouble.
