GSR intake is slighter shorter and bigger in diameter by few mm.
I've used both intakes on my SOHC 4G92.
Not sure about MIVEC 4G92, but for SOHC version, you need to machine a pc of groumet to close off the EGR jacket at the head.
My 4G92 SOHC engine was Turbocharged, so I went for biggest manifold I could find (MIVEC overbore 65MM T/B + GSR intake)
For NA engines, need to maintain V/E. THerefore, going for the biggest and shortest intake is not that good an idea (unless matched with complimenting cams, extractors, gear ratios, A/F, etc)