I have no idea about the NSX really. Been testing it a bit, but nothing big. But on the GTR even it started to use rear tyres more than the front because it spun more. So I went for a more aggressive LSD. I used to run a really low numbers there on medium and soft as the turn in on those wheels were just not present with a "normal" setup.
I went back to stock on the LSD and turned it up instead of down, so the work now is to find the balance between turn in and not spinning.
So a answer to JoeTruckV8, try change the settings in the LSD and keep 1st and 2nd gear a bit (very) long. Maybe even third gear. 4-6 shouldn't really be a problem area.
My LSD settings for GVS is so far 15-22-15 and I used to run 5-10-15 with small adjustments through out season 3. With the new settings I have no problem with spinning up my rear tyres.
To Arkano, you also could test the LSD setting, the higher the number the more under steer the manual say. So finding the balance is just as hard on all the cars now. What you explain have been present even on medium and soft, but the tyres have covered it up some. But we have seen more tyre wear on the rear on the NSX and that means it have less control of the rear end than the front end.
Get that rear end to stick and you could be super fast for sure. Maybe even get control of the tyre wear.
This could actually be easier than with the GT-R as to get grip on the rear you get more under steer, and the GT-R already under steer.
But I have no experience with the NSX, but I though you teamed up with Falcon already.. with the ARTA. I know Falcon have some experience with the NSX and the hard tyres. Should get some help from your team mate