Hey man i own a gts4 and been thru this exact problem..
they have a full gtst mounting setup (eyeball sockets)
yet as said on the post before the gtst struts are much longer then gtr ones and the gts4 for some reason runs a gtr strut setup on gtst mounts
what i did was give justjap a call and basically order gtr coilovers but got them to swap on the gtst mounts, it cost me a bit more but looks a hell of a lot better now
considering before it looked like i was a speed boat while driving..
oh and btw running gtr coils on the rear i reckon i could squeeze out about an inch or two of tucking on my rims haha
but yeah give justjap a call and get them to put gtst mounts onto gtr coils..
hopefully that helps a little..