16v not even a question. You will put it in and wonder why you never did it sooner.

I personally run one 16v D1600 XS Power battery with a 150amp (overkill) powermaster XS Volt one wire alternator and use an XS power intellicharger which is capable of charging 12v, 14v, and 16v battery. I run a K&R delay box, trans brake, line lock, air shifter, LED dial board, CVR water pump, maradyne fan, aeromotive fuel pump, and tail lights. When my car is running and everything is turned on, at a 1600 rpm idle, my battery has 18.5 volts from the alternator. I used to run no alternator and only charged in between rounds and still had ZERO issues with 16v, however, I converted to an alternator a few years ago and I will never go back. I am running 528 Cubic inch wedge, 14.2:1 compression, 850lbs of open valve spring pressure, 112 octane race gas, MSD 7AL2+, crank trigger, 37 degree timing. I still typically charge my battery in between rounds just because when there is a lot of down time, why not. However, once I get into a hot lap deal, I never have to worry about my car starting and once it fires, it gets juice from the alternator.

One thing to be careful of if you do switch to 16v, DO NOT CHARGE YOUR BATTERY WHILE RUNNING ACCESSORIES. So if you are running water pump and fan to cool car down, cool the car down then plug the charger in. You will fry your water pump if you charge and run the water pump at the same time. Mezeire warns people about this on their instructions. CVR says you can run the water pump and run the charger, but I have found that it will cause premature failure so just simply stay away from it.

I currently have a friend who runs two 12v batteries and has had issues with the car starting when its warm constantly. Tried different starters, different gauge wires, tons of grounds, kept a jump pack with the car like DVW said he does. He also runs low compression and alcohol, so he isn't running accessories in between rounds. He has tried multiple different batteries and the car still doesn't seem happy even with 1000 CCA batteries. We suspect maybe keeping heat in the car because the alcohol runs so cold could be causing him grief, however, I have been on him for years about 16v. This season I plan to lend him my spare battery and let him try it and I can guarantee once he puts it in, it will not be coming out.