For the rear lip you need the ss bumper. You can attach it to your pre-existing bumper, but it will not line up properly (overhangs into wheel wells, I know because I tried). The front and rear bumper are easy bolt up replacements. Only takes a couple hours to swap them and are held on with just a bunch of clips and a couple screws. The side skirts are the worst to install. You need around 15 clips per side to hold these on as well as need to cut to wheel wells or buy the replacements to make everything look correct. The installation requires 1/2" holes to be drilled into the body of the lower model cobalts to attach them correctly. You will need to measure several times and take your time when doing these; you do not want to mess this up. I took mine to a professional body shop buddy and he took 4 hours to install these; measuring over and over again. Even when he was ready to drill he drilled tiny holes first, lined it up again just to make sure they were in the correct location before finally drilling the large holes.
If your talking cost it is pretty expensive unless you can get deals like I did. Here is what it cost me:
Front Bumper & Lip - $500 insurance deductible (Also includes radiator & a/c condenser)
Rear Bumper, Rear Lip & Sides - $250
Paint & Installation - $700
NEW COST - Prices from GM Part Direct
Rear Bumper - $323
Rear Lip w/ grilles - $290
Front Bumper - $297
Front Lip - $202
Side Skirts - $231
Paint & Installation - $1165 (Estimate. I got 40% off from the guy that did mine)
TOTAL $2417 + Shipping for parts
I got lucky and happend to find a 2.4L SS/Sport front end for $200 shipped on ebay with minor damage(one scratch and some paint transfer) nothing a little touch up paint and polish couldn't fix. So keep your eyes open.
and Biniecki every time I see your sig I think you're drifting lol
i'm going the ss/na route. i have an 06 ls and i've got the ss/na front bumper on mine at the moment, got it from an insurance clain as well, and this summer will be adding the side skirts, but i also got really lucky. one of my good buddies, R.I.P. Bryan, gave me a set of side skirts from his ss/na. they are arrival blue now but all i have to do is paint them and mount them. as for the rear i'm not quite sure what i'm gonna do. i'm thinking about custom fabbing a diffuser. won't be too hard, just finding a way to mount it.