I'm sure this has been covered but I can't seem to find the thread.
What are the pros or cons to leaving off the foil backed plastic shields when taking off the under shield. I just left mine off when I stripped and painted the tins. No mileage on it yet. I want to run cooler, and am planning to leave the under tray off this time. Are these panels for heat or the Swiss sound regulations?

I also have seen pictures of heat insulation on the flex stainless section of the rear oil pipe. My car does not seem to have had this from new. Is it necessary?
92 C2 with 37k. street use only.

 

About the plastic shields, they're really heat shields and they are in there for a reason: to keep heat from the exhaust away from the heads. So in my opinion put them back. About the undertray.. yes leave it off so your engine runs cooler, not needed unless your're driving at high speed (search for undertray and have fun)

 

I just figured out the search function, so I can take it from here. I think I will put them back on at least next to the cat.
thanks for ther response!