Andy
Yes the best bang for the buck is the pvc and the cone filter.
Joe,
On my brothers 97 3.8 there is a plastic cover over th throttle cables on the throttle body, that doesn't melt. The air box itsef is plastic, this doesn't melt. Look at most new cars, noteably the new t-birds, corvettes, impalas and such. They all have plastic covers right over the engine and these dont melt. Under the upperintake, the fuel rail harness wires are wraped in plastic tubing and this doesn't melt. So I don't believe you will have any problems with pvc.
Jim