let's see if i am understanding this correctly:
basically you have just run more than one ground wire from different locations in the engine bay to the chasis and block right? so if i have lots of the thick ground wire laying around i could do this? or is there some kind of transfer box or adapter that is also nessecary? not trying to start a fight or anything, just a little hazy as to why someone couldn't do this on their own and have the same results.
your description of the effects sound good though, might have to check it out if it's only $100.