1. Improved Stopping Distance

When I first towed my rally car with my Nissan Pathfinder, I had to be extremely careful with my following distance. There was so much sag in the rear of the SUV that it affected breaking efficiency. Most of the braking power is on the front wheels of a vehicle. Because most of the weight is over the front wheels, you have more effective braking when applied to the front wheels. When the rear end sags, you are doing the opposite. The weight is concentrated on the rear end of the car, and the rear brakes need to do all of the work. If you try to brake really quickly in this situation, you will notice that your front brakes will be easier to lock up because of all of the rear weight transfer. This just makes for an unsafe trip.

Air Lift's 1000 series air suspension kit, also known as a rear leveling kit, lifts the rear end of the vehicle up to spread out the weight more evenly. This puts the weight back onto the front end of the vehicle, which lets your brakes do their job more effectively.

2. Adjustable

Driving to work today but towing your boat tomorrow? No problem! You can inflate the air bag springs using the regular Schrader valve included in the kit just like your tires. What psi should you run in your air bags? The instructions said to always have at least 5psi and a maximum of 35psi for my Air Lift 1000 kit. I leave mine at 10psi while I am just driving around and increase it to 35psi when I tow.
When I installed my valve, I wanted to maintain the factory look, so I hid it behind the fuel door.

3. Improved Comfort

Even if you are not towing, I find that leaving 10psi in the air bags makes the ride more comfortable. It firms up the suspension and reduces the bouncing that persists after driving over speed bumps. Adding the air bags improved the ride much more noticeably than replacing the shocks and struts, which I did earlier this year.

4. Easy To Install

Air Lift makes air ride kits that are specific to the vehicle you have. I bought mine from Amazon. All I had to do was put in my 2001 Nissan Pathfinder in the vehicle filter section on this page and they had it in stock.
The procedure was fairly simple for the Pathfinder:

1. Lower the rear axle by disconnecting the shocks and panhard rod.
2. Remove the rear coil springs.
3. Remove the bump stops.
4. Drill out a 3/4" hole at the bottom of the spring seat.
5. Place the air bags into the coil springs.
6. Reinstall the coil springs.
7. Route the air lines and install the Schrader valve.
8. Reconnect the shocks and panhard rod.

One thing that I will point out is that it required me to use a 3/4" drill bit/hole saw. Luckily, I had a stepper bit of that size already, but it's not common for a lot of people to have a size that large.
Here's how it looks after it's installed:

5. Inexpensive

Even if you do not tow very often, it's worth getting this air suspension kit because it's so inexpensive. Just think about it, for under $100 here on Amazon you are helping protect your vehicle, your payload, other drivers, and of course yourself! It's a small price to pay, but the confidence and security you will have while towing will be more than worth it. Even if you need a professional to install the kit, don't expect more than 2 labor hours for this upgrade.