I am pretty sure I am correct when I say this but it would be best to confirm with someone like Stu at MSD....

With the Pectel Super 8 conversion (8 injectors) the software cannot run closed loop fueling (lambda) as it is incapable of doing so.

If you want closed loop, you'll be better off sticking with 4 large injectors and having it mapped with closed loop on the Webber software already in the ECU. That way, you don't have the expense of the 8 injector set up (4 extra injectors, the manifold, the fuel rail, the regulator, the wiring, the ECU mods, the induction pipes (if using the RS500 set up), the throttle cable bracket). Obviously a different story if you're running an RS500 anyway.

You could always speak to Mike Rainbird about the RP Labs L8 modifications. This raises the spec of the L8 to beyond the Webber P8 Escort Cossie ECU.