Would the rear sway bar from a coupe S fit my 08X? I was reading from some Google results but was not 100% sure of the fitment.

I need to do some more research to see if finding one on eBay is any cheaper than getting a new aftermarket set.

 

Absolutely will fit. I bought mine brand new, had it installed for a couple hundred miles but it made the rear too rough for where I lived, so I put on the base rwd swaybar which is softer.

My coupe S swaybar with less than 200 miles, with the rubber bushings I bought is for sale if your interested.