Don't forget the '97 has alot of other changes as well besides the tranny.
From the FAQ:
Changes for 1997
-Three new colors: Kaiser Silver, Monte Carlo Blue, Spa Yellow
-Coupes can be special ordered with either a black top or a body color top; -Ts still have body colored roofs
-New wheel color on all wheels: Blades Silver (a bright machined/brushed looking finish)
-Larger front and rear brake rotor diameters and rotor thickness. The bracket and the rotors are the major change
-Front caliper pistons went from 40mm and 34mm to 40mm and 36mm.
-Larger engine displacement (bore increased from 90mm to 93mm) from 3.0L to 3.2L on manual transmission cars. Model number for new engine is C32B.
-Horse power increase from 270 hp to 290 hp and torque increase from 210 lbs-ft to 224 lbs-ft (manual tranny)
-Different exhaust manifolds, now stainless steel and free breathing
-Different cylinder linings, fiber reinforced (FRM)
-Larger intake valves
-Different head gaskets
-Larger connecting rod bearings
-Numerous emission control system changes
-Six speed manual transmission - 6th gear is engaged by a solenoid. The gearshift activates a switch to change gears.
-Double synchros on 3rd through 6th gears
-Lockout of reverse gear above 12mph
-Dual-disc clutch changed to a single disc clutch
-Dual mass flywheel
-Larger diameter spare tire to clear new brakes
-Stronger, thinner aluminum body panels
-Heat absorbing glass instead of bronze glass
-Immobilizer anti-theft system with coded key using an electronic transponder. No more all-metal keys.
-Ignition switch light went away to make room for the immobilizer antenna.
-Improved NVH (Noise Vibration and Harshness)
-The final gear ratio does not change, so 6th gear in the 1997 NSX results in 6.9% higher vehicle speed than 5th gear in the 1996 model.
-New aluminum alloy in selected body areas to reduce weight and increase rigidity
-Larger spare tire size (from 15 in to 16 in diameter)
-Refined electronic power steering control
-Revised shape of the front spoiler
-Refined ABS braking system
-Improved Traction Control System (TCS) with new control logic