Doesn't painting PVC piping actually make it weaker? I'm sure if you use the header paint to keep heat out it does its job, but when I built my potato launcher it was highly recommended that we don't paint PVC due to the weakening of its structure.

I'm guessing it probably wouldn't matter if its an intake rather that's not dealing with too high of PSI, instead of piping with high pressures of water or in my case combustion.