camira delco computer is the best, cheap way to do it (especially if you can get your hands on the kalmaker gear to do the tuning without having to purchase it)

do some searches they are hugely popular,

can often get the ecu and loom and all sensors quite cheap

i did this, worked well, but even still paying people to tune it i think i would have got a better result with a full custom ecu for not too much more money

my brother recently bought a self tuning fuel only kit that was pretty sweet, cant remember name though, he put it on a 308 in his surf