I bought a set of yellow top Optima batteries and have installed both on a 2001 Tracker V6, does anyone know if I can upgrade the alternator like to other Trackers?  I have a lot of lights plus the winch so I want power.
The rear battery installed beautifully by welding a plate to floor board with preinstalled nuts, removed the insulation from carpet and the battery box fit perfectly without having to cut a hole in carpet.  I am still deciding on how to run the Painless Wiring harness and route the large battery wires through the plastic trim so it looks decent.

So it's bolted down in the pic? And now my stupid questions- why do you have the terminals inward? why not have terminals on rightside*?

Look's nice, don't forget a correct type extinguisher since it's inside the passenger compartment...

*wouldn't it keep the wiring closer to body panels, out of the way, and be easier to hide? I would reverse application, imo.

I do not have a good answer for terminal location, that's why I queried you guys, guess I'll be rotating battery.  I was going to go right through the plastic over the wheel well with grommets.  Yes, it is bolted down, made a paper template, laid the carpet down, slowly rolled carpet back to mark and cut the padding with scissors and just used my thumb to remove the contact cement holding padding on it made the carpet very thin in that location.  The plate under battery is welded to floor board and we drilled out where nuts are welded on, this way you do not have to crawl underneath to hold the nut.  I have added a pic of the roll bar mount, I have some incorrect things on the mount like shear plate width, but it was my first one.

Reasonable- I'm a newb, so I only asked in case there was a reason for it.

Otherwise, still think you need an "ABC" extinguisher inside. Just pray you dont need to clean up the sticky mess after discharging.

Maybe cap your top terminals and use side terminals? Drop the wiring to the floor and notch the bottom of trim to get wiring under/behind with minimal carnage to the interior trim.

You are still going to have to drill a rather large hole in the body to get the positive battery cable out of the cabin, a 1/0 or larger cable will be required. Dont try to fit such a large cable thru any of the firewall grommets. Use a very short 4 gauge cable to the body for the ground(one of the rear seat mounting bolts will work well) Make sure to also install a fuse/circuit breaker just as the positive cable leaves the battery.

I was told to get wire from a welding supply company, supposedly it flexes better and has a shielded jacket.  I will report back if I find this to be true and cheaper than battery cables.
My fire putter outer will be mounted to roll bar whenever it is finished.

talonxrtacer - thanks for the seat bolt idea, I would have missed that and drilled a hole for no reason.  I was thinking of drilling a hole for cable somewhere towards tail light, up high so if I ever get stuck water and mud will not get in and then route cable along frame to engine bay.  My Tracker has cabin vents hidden under rear bumper sides, so when you shut doors the air can escape cabin, perhaps that is an area I will look at.  Then when I rotate battery, ground will be close to seat mount and positive cable will route nicely towards back of vehicle.

Welding cable or high end auto amp cable works the best as both are very close to the same construction.

That air vent has a one way door/trap to keep weather/water out. Best to drill it's own hole and use a grommet and sealant. Monster cable does make a firewall/bulkhead clamp grommet fitting that works very well, a tad pricey but works and looks good.