Get the biggest one that will fit, but your stock battery might work fine too. The alternator is a big player when winching and if you are loosing power you can stick a twig in the throttle body to bump up the idle (not IN the throttle body, but you know what i mean). Ive had a red top in my mustang for a couple years now and was amazed on how fast it turns the car over, even when its been sitting for a month. I used to have a yellow top, and it worked fine but I like the red top way better. I know some guys say that the optimas are now made in china and suck, but they seem to work great for me. I'm not sure that the people that spread these rumors have actual experience with these batteries. (you know how easy internet rumors spread) When my battery dies in the jeep, I'll buy a red top for it.