I am not really an expert on how it works to be able to recommend too much.
I think they need another 50HP out of the motor at least. I think they need to get more out of the batteries, but I don't really know what is possible. I feel like they need to be under 3 to 60 just for marketing.
The reality is they went a different approach than everyone else. Some like it, some don't. Some might say a 570 is much faster for the money, but the 570S can't cruise around in silent mode like KITT.
Most people buying these cars will NEVER drive them near their potential.
I think we will see some mods to put the NSX well up over 650HP from the motor. That should be interesting.