What could be causing this?
 

When I purchased my car you could tell it had a rough life by the suspension. I was kind of worried about the engine being ragged out but that doesn't seems to be a concern no more. The engine runs fine, it is not burning or leaking oil at all. But something I have noticed, when the car is pushed to WOT sometimes smoke will pour out of the exhaust. I'm not sure what it is since both times this has happen at night. I'm guessing the smoke is un burnt fuel since the injectors are suppose to be over sized. Do I sound right on my assumption or could it be something else?

I wish I could tell what color the smoke was. But their was a truck behind me and with the headlights on, the smoked regardless of what color it really was looked white. One thing I did notice was when I pushed the car to WOT (from around 20mph), the car seemed to hesitate for a second. Like it was over loaded or loading up with fuel, then the car took off and the smoke started pouring out the pipes.

finding out what color smoke it is would be a good start.. black, blue, white etc etc

Do you know if it was programmed for the larger injectors? Are you sure they're larger? If you can take a picture of them, I can tell you what they are... or at least if you can tell me their color/numbers on them.

My guess is that your car is running rich and that is black smoke (unburnt fuel) coming out of your tailpipes.