I'm wondering, WHY would anyone need to run a 200-240 amp alternator to their car?? Is everyone running dual Weldon fuel pumps? That'd be the only real reason you'd need it - and you would have to upgrade your battery (or batteries) to support it.
The factory OEM battery cable uses 8 gauge wire, not 10 gauge wire, to the alternator. The starter feed is 4 gauge.
The standard ground connection to the chassis is 10 gauge and the negative battery cable to the block is 4 gauge. If you've added current-hogging accessories to your GN, it would be wise to add an additional ground between the engine block and the chassis - use a BRAIDED flexible ground strap or arc welding cable with soldered terminals.
8 gauge wire will support 75 amps, 6 gauge, around 100 amps. With a fully charged battery, your stock alternator never delivers more than around 55 amps, even with every conceivable accessory turned on full-boat all at once. This would include low impedance injectors, high output coil, upgraded fuel pumps, power windows up all at the same time, electric seats moving, and so on.
That is, unless the battery is deeply discharged or has shorted cells. Then the alternator goes into overdrive.
You should never need any more than a 6 gauge cable connecting the alternator to the battery, even with a 200 amp alternator. I'd recommend 6 gauge if the battery is in the trunk, since it needs to travel maybe 14 feet to get there.
some guys car starts better with a larger wire from the alternator to the battery--------pretty wierd since the starting current all takes a different path on another wire altogether----------john-------can't agree with you more--------this thread is ridiculous---------been hearing it from the stereo guys for 20 years-------it displays total ignorance of simple physics--------anyone wanting to prove this nonsense to themselves can do a quick simple check----------just take one half of a jumple cable set and fasten one end to your alternator output stud and the other to the positive post on the battery---------see if anything changes--------NOTHING will change unless you have a bad crimp on either end of the factory wire in which case all will be just fine if you install a new connector
------------to most electricity is like magic since its invisible and it conjures up voodoo fixes......................RC