Changing ground wire from battery?

When you guys install a amp, do you update the ground wire from the battery to the same gauge as the power wire you run for the amp?
thanks

I usually don't, unless I have to alter the stock wiring to the battery.  You usually want the ground from the battery to be the same size as the positive to the battery.  You will also want to ground your amp using the same principle (with the same size wire as the positive to the amp).  If you're running 4 gauge to the amp, use a 4 gauge ground for the amp.

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Squirrel
"No more Cpt. Kirk chit chat"
If its too loud, then you're too old
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ummmm....  I am really curious to know where the chassis ground is going...  maybe THE BATTERY?!?!  Yes, absolutely, upgrade all of your wires, but if possible, use the factory locations.  A little thought into the operation of a car's electrical system will yield amazing insights.  Just because the alternator lead might be a wimpy 12 (or 10, if you are one of the lucky ones) gauge wire, it is grounded through the chassis, which has about, oh, A MILLION times the current capacity of the alternator output lead (technically, it is grounded with the same size wire, because the engine block is grounded to the chassis, usually through a small, short grounding strap).  The reason for the small output lead is because the alternator only puts out THAT MUCH CURRENT.  Pretend it (the alternator) is not there, and the battery can continually recharge itself forever, and never go dead, now hook up an amplifier to it, (mounted in it's happy home) using a 4 gauge to the positive lead, and a 4 gauge to the chassis, but use the skimpy OEM 10 gauge for the ground to the battery...  hmmm, equally sized wire throughout the system makes a little more sense, doesn't it?  There is a thing called thermal dynamics that comes into play here, and ideally, whatever size wire(s) you are hooking to the positive terminal, then you will use an equal or greater number and/or size on the GROUND (or negative) terminal ALWAYS!  This will usually help all of your components run better, and if you are using the factory ground points, then when you remove the OEM wires, you will be able to make certain you are connecting to bare metal by cleaning the ground point.  This, in turn, will ensure minimal noise entry into the system, as well as ensuring no current starvation for your components...  ahhhh, efficiency.  I will always strip out almost all of the wiring under the hood, and replace it all with at LEAST a wire size that is 1 or 2 steps higher.  Ex: replace a 10 with a 9 or 8.  My only excepton to that rule is the starter and ground straps, and those get replaced with a 4, no matter what.  What I am really trying to say, is "yes, replace the wires..."

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."