Convertibles have started to be received, and others on the forums have had issues with 3" cat-backs on the 2015 GT convertibles clearing the extra bracing. I don't think these will fit the convertible...if not, you may want to update your website to specify it is for Coupes only. :-)
While Gibson has not gotten their hands on a convertible yet, based off measurements and schematics they have, they believe it will still fit. I cannot confirm that 100% unfortunately until they can get a convertible at their facility.