Okay so I had a new system installed in my 95 Jeep Grand Cherokee 6 months ago and here is what I got.
Kenwood Excelon KCD-X890 Deck
Focal Polyglass 130 V2 (tweets and front doors)
Focal Access 165 CA1 (rear doors)
Run off an Audison SRx4 Amp
10" Boston G5
Run off an Audison SRx2S Amp

I noticed after the install that my lights dimmed when at a volume of 20-25 and my voltage gauge would bounce around 10 volts from 14. I did some checking and found that a new alternator would likely be necessary, so I just had my alternator rebuilt to throw off 150 amps up from the stock 90 amp.
After this little addition I noticed 0 change in performance, in fact it appeared to be worse then before. I figure worse because now my Jeeps computer will randomly reset itself, the same way it does when I disconnect and reconnect my battery. So I checked around online (finding this site) and found that I would likely need to upgrade the Big 3, so I did, to 4AWG wiring. I added the 3 wires leaving the stock wiring in place.
Now after all this I am still having problems. When I did the Big 3 upgrade I went Alternator to Battery (+ to +) even though my alternator's positive is connected to a fuse box, Chassis to Engine and Battery (-) to Chassis. Is this right?
The only thing I haven't done is replace the battery and I am hoping I wont have to but will if necessary. The reason I don't want to is out of ignorance. I don't know what the difference is between a $100 Costco Battery and a $230 YellowTop battery is. And I don't want to upgrade it if I'm still going to have problems.
I am looking for some advice on things I should be checking or changing and maybe an explanation on batteries.

 

Bad grounds....corroded wiring power wire is too small. . battery would play little effect with a 150 amp alternator.

 

My wiring is new so there isn't any corrosion yet, I don't know what you mean by bad grounds and what size alternator do you think I should be dealing with?

 

Check your grounds to make sure that they are clean, i.e. no corrosion, paint etc. How old is your battery? It simply might need a replacement, not necessarily that you need an Optima, but it may just not hold a charge anymore.

 

When you did your big 3 for the grounds, did you use the factory ground point?. here's a hint, it's painted. you have to do a little sanding to get to bare metal. the add your ground wires and spray wit some battery terminal sealant, or rustproofing grease. Also make sure your engine to chassis ground is a good one.

 

Are some batteries better at letting power pass through them? Can they act as a bottleneck to the power that the alternator is supplying when the amplifier(s) are working? Just curious.

 

Have you check the charging voltage of the alternator at idle?I had my alt rebuilt and noticed that at idle(700 rpm) that i was only getting 12.0v if I rev up to 900rpm I get 14.0v If the charging voltage drops to low like if your lights are on and the fan is running and the system is on the computer may reset. I had to adjust the idle to correct this problem. But it could still be the wires so check those too.

 

a battery shouldn't be part of the consideration for a daily driven cars sound system. I like Optima Red tops though. they last forver, you can drain them out a unc of times and your call will still start when it's minus 30.

 

Thanks everyone. I will go back and check all my connections and voltage output. Ill get back to you when I've completed everything.

 

Well I did everything that was suggested and found that my battery was weak but that system drew just a little more power then I was putting out. I didn't like the cap idea because I have read a lot of threads about how little they do for the system.
I did find an alternative that works pretty slick. It's a power cell from Kinetik, the HC600.
Here is the webby if anyone is interested in the product, KinetikPower.com, i'd have linked it but I haven't posted enough yet.

Thanks for everyone's help, I am positive my system runs 100% better do to all your insights.