There is no point in getting a diffrent ECU at all - performance wise - if thats what you mean. The stock ECU will handle light boltons and tune them by themselves in closed loop. You might have a slightly lean open loop if the intake is really efficient, but normally the P73s run rich in that end anyways, but if you need tuning, your P73 wont be the ideal solution anyways. You'd wanna go OBD1 with say a P30. I reccommend P30 over P28 because it has the KS input. If this is greek to you, I suggest you take a look at the various PGM:FI forums around.