See smoke in headlights behind me

[rraccerr]

After two years, I finally was able to have my truck serviced at Mr. Haggs shop. Wonderful people. Wish he had more than one shop, but , being super busy, he made time to fix my truck and give it the Heaetbeat it needed.
But scratching my head about one detail I could not don’t get answered, maybe because I asked a lot of questions and confused the team.
My truck smokes and I see it at night going up hill with headlights behind me. Not visible during day could it be my cans need to be hollowed out?

Than you for any reply.