efi as in ofab or aftermarket management,ofab you could do for under 1k but as far as i know only msd(of the reputable tuners) can map it and that would mean no set ups at ava no more unless you go for ava's own which is 2.5k supply and fit last time i asked( i keep askin hoping it will come down a little ) then takin into consideration the buying of a new turbo and then the gearbox your gonna need too want my advice keep the money sell the rst and buy a cossie,at least the cossies gonna take the power where as the rst just can cope with that power never mind anymore,you could get another 30-40bhp but much of that power can you put down,or you could just bolt on a t3 and enjoy the new found torque in the mid range(though T3 RST just disny sound right),i for one will not be spanking anymore money on my rst and its only a matter of time before i break it and buy a cossie

speak to alan and discuss your options,he would do you a modded t3 like he done with andys,max boost by 2800rpm right to 7200rpm where he made peak power,now that is a powerband