280 inj engine

What modifs can one (inexpensively) do to improve the torque on a standard 280ZX engine ?

BMW throttle body ?

Has anyone tried using an LD crank to get 3 or 3.1 litres in a ZX ? If one touches anything, can the standard injection cope with increased demands ?

If not, what are the alternatives ?

I suspect it can't but can one replace the injection system with a more modern one ?

Thanks

ps Is it a real gain to replace the variable assistance re-circulating ball steering system with the rack and pinion one ?