DIM headlights?

So recently on of my headlights went dim, not out. The other side works fine, ive checked the fuses and the wiring itself, and replaced the bulb so im stumped as to what could be making the light DIM without making it go out completely

So you replaced the light and the new bulb is dim also? I would start by checking the voltage at the bulb. Possibly a bad connection somewhere. Is the high beam dim on that side also?

This happened shortly after i put the headlights back on after my intercooler install. The brand new bulb is dim also and the high beams work fine on both sides