Any true cold air system you get is going to require a smaller battery. The hole that connects the stock airbox and the intake resonater is too small to fit a 3" intake pipe into the fenderwell. So you need to enlarge that hole by cutting it, and by doing so would normally run into the battery, which necessitates a smaller battery. You also have to cut into the metal plate that the battery sits on. You can definitely find smaller batteries that will run the same amount amount of power ( or more power if you want to spend more money ). I would be more concerned with the cutting of the metal than finding an adequete battery.
I meant to post some pictures for somebody not too long ago. Hopefully I can remember to take a few this Thursday. I didn't have to get a smaller battery, but I did have to move my radiator overflow tank.
I got a 92 g and i got the HS CAI a few months ago and you don't need a smaller battery. But when you cut the whole bigger make it bigger towards the back of the car. You get a lot more room and just slide the battery to the bottom left corner.
u dont need a smaller battery. You just need to slide ur current bat over to one corner of the tray. You do need to cut tho, to make the whole for the pipe bigger. for more info search for hs cai or sumthin, this has been discussed a lot. any questions.. pm me.