Good question. I have the CDC spoiler on my 2010. Car is lowered 1" in front and 1.25" in the rear. The dead center portion of the CDC spoiler is 5.5" above ground. The extreme ends are 7.5" above ground. What might be of concern is if the street legal splitter was added to the CS spoiler.
I have the optional 2.5" brake cooling silicone hoses on my CDC. They are now advertised as 3" hoses these days. I think the CS spoiler has the foglamps..where as the boss version gets the cooling ducts /foglamps..but not both.
CDC also has a lower foglamp kit for their front spoiler...but the small rectangular piaa bulbs sit in front of the cooling duct rectangular cut outs.
I got around that by mounting the lower piaa foglamps slightly inboard. So I could have both foglamps and cooling hoses at the same time.
Clearance has never been an issue with the CDC..and car lowered 1" on the front. I stopped at the bottom steep ramp of a local underground parking lot at midnight when I 1st had it installed....got out and measured the space..and it was 2.5" between ground and center portion of the CDC.
I had a CDC classic spoiler on a '07 GT for several years and just recently had a CS bumper cover install and the CDC classic sticks forward and down farther than the CS. I would scrape the CDC at several places around town but have yet to have a problem with the CS bumper.