Basically you need to accelerate hard in 3rd gear from around 200rpm and hit about 4500-5000rpm and then go to select 4th quickly, you should notice that the revs will not drop back and may even increase slightly, and the car will continue to accelerate in 4th for a few seconds. Be warned extreme speeds can be reached quickly.
Another trait is the on a dual carriageway who cruising at around 70mph in 5th or 6th try lifting off the accelerator you should find that reeves do not drop for several seconds.
The original ECU is largish a triangular shaped black and sliver box that is in the fuse box under the bonnet, I thing the MBE is smaller and a different shape.
Adrian
Buggered Off, to a modern none leaky car, heart's still ticking
