If you don't have a DPF - and you don't, DPFs are only on STX Dual Cab automatics from 2006-ish to 2010-ish - then SOME smoke on acceleration is perfectly normal. You'll see it even more at night, the headlights of the car behind will often make even a small amount of smoke look like a cloud.
Injector cleaner doesn't always work, but it is always a good first measure because for a small cost, it will remove small amounts of muck from the injectors that might be causing the injector to spray poorly into the cylinder. The best clean is through removal, where the injector can also be inspected for damage. Small pits on the surface of the injector port can cause erratic spray patterns resulting in slightly less power and more smoke, and these would require replacement.
You could just say to hell with it and toss them out, but the best thing is to clean the air filter, making sure there are no other air intake restrictions and your airflow sensors are clean (electrical contact cleaner works well) then compare how yours performs alongside a similar vehicle.
Injectors from Nissan aren't cheap. Get "genuine" ones through
Nizzbits instead of a Nissan dealer. I used "genuine" because Nissan don't make their own injectors, they use a third party anyway. I can't remember who makes the injectors, it's a company starting with 'S' I think - someone else might remember and post it up.
