1996 GMC C1500 96 Sierra - White Smoke

I have a 1996 with dual exhaust beginning with dual headers at the engine. The exhaust pipe that runs to the header on the driver side of the truck is issuing a white smoke. Not real thick, and it does dissapate fairly quickly. However, it's just the one pipe doing it. I seem to lose a little engine power here and there but nothing major. Oil has been changed, I had an external coolant leak but fixed it and fluid level seems to be holding now. Ideas?