The 2wd are more prone to piston slap, which was cured mostly on later 4wd pistons by resiting the wrist/gudgeon pin a minute amount.
The pin is not in the centre on the 2wd as they are all offset to varying degrees.
Your smoke sounds like guide wear, although the rings and turbo can also contribute, how many miles has it done, as the heads don't last well at all wear wise.
As for the fuel pressure, this will be dictated by the author of the chip, so best to contact them, as they may have written it for a different pressure/co.
tabetha