Even if the HKS Type R is slightly larger than the GReddy 4-row, keep in mind that the GReddy 4-row's piping will mate right up to your T-78. If you run the HKS Type R with the T-78, you'll have to fab some custom piping, since the HKS header positions the turbo differently than the GReddy header. The GReddy 4-row is huge. I'd recommend sticking with it.