If you are to run 2 air zenith ob2’s will you need a larger alternator and bigger battery.
They will draw 70 Amps max. If your battery is in good health you shouldn’t have any trouble with a standard system. You’ll generally only need a HO alternator if you have continuous high load on the car’s electrical system. If you run the OB2’s for long periods you will benefit from a better alternator but for short term loads it’s not necessary.