The T25 flanges are exactly the same the difference between the -5's and -7's is the actualy inlet hole size in the exhaust housing -7's and -5's have a hole of 38mmx 45mm
the GT28R run 38mmx49mm
the flange bolt pattern on both is 73mmx40mm
they will bolt on to your manifolds so to speak.. however the dump pipe flange is different
water lines and oil lines would bolt up.. however i dont think the 28r has the 2 bolts on the compressor housing to match up with the factory water and oil line that loops around the core to make things easier(apprently)
you'd be much better getting a pair of -5's or -7's as they do bolt up with all the factory gear.. only thing that needs modifying is the oil drain as the holes are closer together from memory however the oil drain issue would be the same with the gt28r
dont think ive missed anything..