Excuse my ignorance, I'm not much of an NSX historian...
But has Honda or any other company ever run any motor other than the DOHC VTEC C30/C32 engine in the NSX platform? Prototype, race car or otherwise? Perhaps a turbo 4 cyl?
For example, in the JGTC series Toyota runs the turbo 2.0L 3SGTE 4cyl motor in the Supra instead of the heavier 2JZ.