I said I would report back what I found out about grounds. First I will say that I have NO experience in running cars anywhere near the power level of Montes stuff. I will also admit I'm not a degreed electrical engineer. I do work with car electrics on prototype and production vehicles everyday. I sought out 3 very knowledgeable electrical engineers that design and work on modern electrical vehicle systems. These guys are not racers but are extremely knowledgeable if the field of electronics. Two of them of the saw absolutely no need for a separate ground cable from the battery to a forward location in the car. The third saw the only possible advantage would be to run a separate cable from the battery to the cylinder heads themselves. His theory was that enough current was being sent through a "race type coil" that it was possible that the spark plug current might possibly corrupt the ground side. Though he thought the possibility was very slight. He also stated that any possible advantage would be lost unless this cable was routed and used for cylinder head grounding (and obviously the starter) only. Everyone agreed on a few things.
#1 Grounds should be as close as short as possible.
#2 Grounds should not be stacked more than a few. But should all be as close together as possible. Such as having multiple ground studs with-in a small area.
#3 The mass of the uni-body/roll cage is more than adequate as a ground plane.
#4 The use of a thermal grease such as Alonox on connections, especially where wiring is bolted to aluminum. This will reduce the likelihood of fretting and heat damage due to thermal expansion and contraction of aluminum.
#5 That cylinder head grounding to the chassis may have the most potential of anything that has been discussed here. The possibility of plating on head studs/bolts may inhibit good grounding of the spark plug, though they have yet to see it in the field.
#6 Do not run any high current cables near sensor or pickup wiring.
Make sure sensor wiring pairs are twisted to cancel magnetic field effects in the harness. A shielded wire as part of that harness with a foil covering grounded at the module end only will act as a capacitor helping disperse noise.

Finally everyone agreed that testing voltage drop on individual circuits under loaded conditions will tell the story if the ground is adequate. Although this could be accurately done with an Oscilloscope acceptable results could be taken with a Fluke meter. The min/max selection will take samples of voltage drop at .01 second while recording.
I hope everyone can gain some insight from this. While I don't think a dedicated ground would hurt, I don't think it is necessary either. In my world budget is paramount. With 25' of #1 cable going for close to $100 that is an area where my dollars might be spent wisely elsewhere.
Doug