Long answer is 'depends'. They will only fit GT-R's RB26DETT without modifying the type of injectors expected. You can get any type injectors to fit any car (within reason) however this will require modifications to other systems in the car such as signal type and injector rail type.
On the GT-S's RB25DET engine the impedence type required by the Nissan ECCS Engine Management system is of High impedence type. Its of low impedence type for the GT-R's RB26DETT.
These HKS injectors are of low impedence which means they are incompatible with the ECU for your car.
Having said that some enterprising people have worked out that you can retro-fit the GT-R's "resistor packs" and this then allows conversion from the high type "switch on/injector pulse signals" from the ecu into "peak and hold signals" required to control low impedence injectors. Obviously this is not so straight forward and requires a lot of indepth engine management knowledge and probably a reprogrammable ecu like a PowerFC or HKS FCON V Pro.
If you'd like to know more about injectors I've researched this quite deeply and have a lot of information i could pass on or add to a FAQ for interested parties to read.
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