Stay away from the china made stuff. IMO, I personally like the products manufactured by UAS (Universal air suspension) . They make quality parts that tend to endure more abuse/use than other brands. I've seen people have bags go out on them while driving and valves/compressors that go bad because of poor quality. Suspension is something I prefer not to cheap out on especially if it is something like airbags.
A good quality kit will run you about $2300 with an air tank, valves, lines, fittings, and compressors. For a bit more, you can upgrade with complementary parts that will add convenience to your ownership experience. I personally would also suggest going with an auto leveler such as the "e-level" made by accuair since it really is not much more than purchasing sending units with a digital pressure gauge.
Traditional airbag setups are manually adjusted via the usual switchbox and you are stuck with eyeballing the ride height and guessing. Over time, you can get an idea of how your car feels and rides. However, it is not very accurate or convenient and can be a bit of a nuisance.
Others install digital pressure gauges to monitor pressure in each corner of the car. For instance, they can choose to put 60 psi at all corners and manually compensating for cargo/passengers by putting more air where there is more weight etc.
Dakota digital also makes an auto leveler that monitors airbag pressure and sends air to the airbag if it is lower than what it is preset (programmed) to be set at for you. This particular system reads off of pressure in each bag and does not monitor height. So if the car is not balanced even though the auto leveler reads each corner as being equal at 60 psi at each corner, the car can still not be leveled especially if there are passengers and cargo in the car.
The e-level kit made by accuair utilizes height sensors to monitor actual ride height. This new system is much more accurate than the dakota system that is merely airbag pressure based. All you have to do is preset your desired ride height (level 1, level 2, and level 3) and go. Once you set it, you don't have to manually eyeball the car and adjust accordingly. If the car is too low on one side or corner, the computer will read it and make the adjustment automatically for you. It's as simple as pressing a button on your radio to play your favorite radio station. All you have to do is focus on driving.
The e-level may seem expensive, but the price already includes everything including the height sensors and sending units. If you go with a digital pressure gauge, the sending units are typically sold separately and will add about $130-150 plus another $200 give or take for the gauge to your tab. In my opinion, using that $350+ towards an auto-leveler is a wiser investment.
You can read up on the difference of varying products here:
http://www.jdm420.com/product_info.p...roducts_id=175
http://www.jdm420.com/product_info.p...roducts_id=174
https://www.universalairsuspension.c...33672a76a18004
Also, you will also have to choose from varying fitting/hose sizes. 1/2", 3/8", and 1/4" is the norm. 1/2" will give you the faster drop/raise of the bunch when hitting the switches and will slow down as you go with a smaller diameter. You can also mix it up and go with 1/2" fittings with 3/8" buffers to allow a fast raise and a slower drop.
You also have to decide how your suspension will be setup. Are you going to use bags with coilovers (goes in place of the springs) or are you going to run OEM shocks? I personally think going with coilovers is the better option because they tend to ride a lot better. However, not everyone can upgrade everything at once. You will also have to have brackets made to put the airbags on the suspension.
There is a bit more to look in to, but I am running on 2 hrs of sleep and have finals the next two days. I hope that helps a little bit. You can view my build-up thread for a basic idea on what I did to get an idea of what you prefer:
Rickdogg's Gen 5 Mild Build-Up Thread and background
I actually have spare airbag equipment laying around and can get you started for cheap if you decide to go that route:
-UAS Chrome 5 Gallon Air tank
-SPD Air Valves
-UAS 7 switch switchbox
-& Misc airbag stuff
Dumped/Bagged/Slammed
Linear Mode
