(In case there's any doubt after reading the statement below, I know very little about engines of any kind, but I can follow directions.)

About 8 months ago I was experiencing regular "pulsing" of my 2001 2500HD 6.6 Duramax (330K miles at the time)when traveling down the highway, and was advised by a mechanic that my Fuel Pressure Regulator needed changing. So me and a buddy looked at some youtube videos and changed it. I put in a stock FPR from the local parts house. And I changed out my thermostat while I was at it.
When I started the truck back up, I immediately saw light-colored smoke coming from the exhaust. I figured it was because now that I was getting good fuel supply, maybe my injectors were showing up as bad.
So I took it to three different diesel mechanics, none who could confirm that my injectors needed replacing. Turbo was fine, (no oil inside? ) The truck runs fine, no rough idle or rpm, zero poor performance. One guy hooked up an analyzer and said that without actually pulling injectors and testing each one, all he could tell me was to live with the smoke. "It's an old truck and it smokes. Keep driving it." My mileage per gallon is holding steady, around 16 in town and 18-19 on the highway if I keep it at 65. Will still pull my 6000 lb trailer on 1,000 mile trips without complaint.
Great, except that it REALLY SMOKES, and is most evident at idle when clouds of smoke fill the intersection. Embarrassing at a stop light. The smoke is whitish-grey, not dark. Certainly not black. I have NEVER needed to add oil. The smoke smells like diesel in my opinion.
Is there something I could have done/not done when I changed the FPR? Do I have to go spend $2000 to pull injectors to find out why my truck is smoking even when there's no indication that it's injectors? Can anyone offer any advice?
One final note: I put on a BullyDog in '05, and it doesn't seem to work anymore. I can't adjust the program. One person told me that could be the problem, that I didn't get it hooked back up right when I put the truck back together.