I installed these calipers + Sonata rotors yesterday and I concur that the GT alloys DID NOT fit
. All were brand new parts (except for calipers) and the pistons hadn't been compressed yet. I had to go and get some wheel spacers (only able to grab 8mm ones) and put them on to get proper clearance. With those spacers, I had only 4mm clearance between the caliper and the ''branches'' of the GT alloys. (I will go back out later and measure the clearance once the piston has been compressed, I doubt there will be much difference).
However, I must say that this setup brakes really well. I love how the brake pedal feels now compared to when I had the Elantra calipers.