The first gen VW Rabbit used a rubber mounting bushing for the alternator.. common problem was bad grounding. Fix was to run a ground strap from the alternator housing to the engine block. Don't know if others manufacturers do the same thing but I saw enough problems with the VWs to remember it, and to check for voltage drop from both alt housing to engine block and alt housing  to bat negative.

I've seen factory ground side wiring to run from battery negative to chassis, and another wire from bat neg to engine block. Then a connecting ground strap from the engine block to the chassis, just to make sure. 

The main point of my post was to point out that resistance measurements aren't very good at checking for bad connections.. I've seen mentioned elsewhere on the site that up to 0.5 ohms is acceptable.. what's the voltage drop across a 0.5 ohm resistance with 25 amps?.. does it look like something anyone would like to measure on their own car?

Jim

jt824 wrote: So when upgrading the big three I am adding wiring to the existing 3 locations and leaving the factory wiring intact correct?

That's the way I describe it, yes.  You CAN replace the OEM wiring if you choose as long as you use large enough gauge to supply the normal vehicle loads PLUS the sound system load.

specvsentra wrote: when installing the big 3 what size fuse or circuit breaker should i install between the alternator positive and battery positive leads??

While it is not 100% necessary to do this, it is always a good idea to fuse any power carrying cable, especially those you have added to your vehicle.  Place a fuse or braker close to the battery side of the cable rated at about 80% of the cable's load carrying capacity.

about soldering... I think there's several variations of what's right. I was taught, to do as DYohn begins. aplly a bit of solder to the tip.

but when adding the remainder of the solder, feed the solder oppostie from where the iron is, to ensure a proper job. It makes sure all the metal is hot, and ready to bond. So if the iron is in your left hand, feed with the righ hand, 180º from where the iron is. and I don't mean on the other END of the cable, just the other SIDE from where the iron rests.