If you're carrying that much weight I would just keep the stock suspension. I would get a sway bar though. Very noticeable difference with it.

 

Air bags for weight..( or the strip)..Air lift 1000 air bags or Firestone Coil-Rite air bags hold 1000# increases no problem..no modificTIONS required other then slipping the bag thru the spring coils and running the airlines which can be run two into one or two seperate( especially good for track preloads). I personally ran the air lines up the fuel fill line and mounted them inside the fuel door, hate having to crawl under everytime I want to add/release air!Ive had mine a good 4 years now with no problems..run ya 80-90 $....
These are the about the same as the 1982 Cavalier bags which is what I ordered back a ways..now they have numbers listed for the HHR,...JCWhitney anyways, either way they do a good job...
I think you could get away with springs because with the bags you could just pump it up to gain more clearance when loaded...like an air shock...( i remember when THOSE were popular!)

 

I assume you're just talking about the rear bar?

 

I have no opinion on the weight issue, other than suggesting getting a small trailer and tow your stuff. However, I just wanted to say that I LOVE my '06 2LT. Mine is a 5-spd manual and it's really cool having a car with leather, heated seats, all the goodies and have it be a manual that gets fantastic gas mileage.

 

I guess the 2LT has no sway bar at all? I looked underneath and didn't see one!

 

Yes it does, built into the rear axle beam. But it can certainly be improved on, by adding an aftermarket one..

I'm not plugging rear bars for anyone, I just know mine has made a BIG improvement in cornering / handling & etc..

 

Keep an eye on tread wear in the rear. You may have to run a couple extra pounds of air pressure to accommodate the weight.

 

I'm amazed how well my new 2LT handles the weight. I just have to grab a rear sway bar because it looks like it doesn't have one! I still have to figure out what I'm going to get for new wheels. The "chrome tech" plastic-clad faces on the 17" rims need to be replaced.

 

Yes rear sway bar. It just bolts right on to the rear axle assembly. Start to finish less than 30 minutes.

 

I got the Progress Technology rear sway bar. It's 22mm diamater. There are larger & smaller ones out there too. Easy installation! The rear of these cars sits a little high (stink-bug) which adds to the body roll in corners. I later added the 1" leveling springs which makes this car handle a lot better!