The Belly Pan is there for 3 main reasons:
1) Preventing rocks and debris from collecting inside the engine compartment.
2) Protecting the hoses from drooping and catching onto road debris.
3) Keeping the engine compartment temperatures cooler= lower engine temps.
The first 2 you can surmise the level of importance. The last item mainly applies for extended Highway driving.
Without the belly pan, hot air can get trapped beneath the hood by turbulent air entering underneath the front of the car. The belly pan works as a wind deflector to direct the air further down the underside of the car.
If most of your driving is around the city at low speeds, you won't notice the difference. But if you plan on taking the car to the track or drive on the highway for extended periods, you should install the pan.
Regards,
David
PENNYWEB/REALRIDE.COM RACING
http://www.RealRide.com