you can buy aluminum tape that is very reflective. heat gun to get the lens off, clean everything up, add tape, assemble with clear rtv. use a rubber kitchen mat from walmart to make a gasket to seal taillight to car.
the ecu does not "think" it is making 10psi, it "expects" 10 psi. these cars do not measure the pressure. they only add enough fuel to cover the air. if you're having problems during boost I would start out looking at the secondary fuel injector. the factory boost gauge is known to not read correctly so there's no point in even looking at it. if you don't want to pay for upgrades to help diagnose your problems, you will not get far with these cars.