Complex subject. No idea what testing is actually done and what the real intention is, performance or appearance. You should still get dust and dirt...
Iv alwasy had this idear of redirect the secondary air pump system to suck from the crank case and vent into the exhaust post cat resulting in a 100%...
Normally a buyers market, rarely a sellers market. I haven't sold a car in many years, bought a few over time and I tend to use the not mechanically...
Painting is the one thing I really need to but impossible when your renting lol
Ones I get my own place I most definitely will be installing a paint...