Its tough to say. What's your definition of "Faster"? -Acceleration, top speed, lap time (if so -short or long track) etc...
The GT500 cars are pretty much Formula Nippon racecars with street car bodies and share almost nothing other than the A-pillar of the production car. The LeMans car was a factory-bodied turbocharged (GT1) car with no power limits and more power than the GT500 cars. It also has a narrow body compared to the GT500 or our FX750 which greatly improves top speed.
In the power department, I think we are good. We still need about $40K for a sequential transmission though, so if you hear of anyone... On a long track like LeMans, the LeMan NSX might be faster than the GT500 due to its higher top speed. While we aren't as narrow as the LeMan NSX, we have more power and 180mph+ isnt a problem, and we will be doing more testing of top speeds and standing-mile events soon.
On a tighter/more traditional racetrack, its hard to beat a 500hp+ NSX-bodied Formula Car. We are hoping in the next year or so to have the opportunity to run at Fuji Speedway and see how our times compare to the LeMans and GT500 cars.
To put things in perspective: at the moment we are very close to current ALMS GT2 lap times and Grand-Am Daytona Prototypes. We look to eclipse those times in the near future. More power, but no sequential transmission (stock) -which almost offsets the power difference on traditional racetracks.
Billy