Compressors

If you want to add air bags to your vehicle, then one of the things you need to get is at least one compressor. That's because a compressor takes the air in the atmosphere, compresses it (obviously) and then puts it into the air tank. Without compressors, you've just got an air tank that won't ever recover without manual assistance, and that's not exactly convenient. 

Now you don't have to run just one compressor, either. You can often get a better deal on two compressors, which Viair sells in a dual pack for less than buying a pair individually. You can do even more if you want, but for most setups 1-2 will work just fine. 

But compressors are essential to your air management system, so if you're bagging your ride, get your compressors now.