07gttom

exactly. a battery is just another loadon the alternator. getting a bigger battery will, in effect, hurt the alternator because now it has to work harder keeping it charged. with a system, the bigger alternator is needed. if you see your headlights dimming, that is because your alternator can not keep up with the loadthat the amps are drawing, and the batteryis nowhelping out.this causes the alternator to have 2 jobs now,suppling the vehicle and recharging the battery. if you are just replacing the ford battery and are running the stock electronics, then use a red top(if you want to spend that kinda cash), yellow tops are deep cycle batteries, they are designed to be used with the car off. can you use them as a starting battery, sure but you will not get the service length from them as a red top. If you are running a high amp system, get a bigger alternator and upgrade the size of the stock power wire and ground wire, so the current can flow better.

warhorseGT

From what I learned:
The standard 800 CCA Optima Red Top fits perfectly even though its a group 34.
Look for a group 40R battery.
I personally havent tried the fit yet-still have the stock battery. I dug up the above info awhile back after having a dead battery.
Hope this helps.

jerjan

I am using Wal Mart's (not walmart brand) 1000 amp crank batteries in two of my cars and soon to be three. They have been just great and carry a three year free replacement warranty! Last time I checked they were about $80