Simply putting in a Motec Computer will gain you probably 10~15 Kw I think with no modifications at all. I have seen a motec computer put into an XR8 sprint but it was combined with a whole host of mods including forged pistons, big cam and was able to achieve 280Kw at the rear wheels. The only reason why you would want a Motec is to gain big power figures from modifications you perform on your engine. By strapping it onto a stock EB GT you would be able to remap fuel and ignition curves to achieve a slight increase in power, it may become even more responsive and better on the fuel economy.