L5,
I would be patient about mods. I strongly second the comments above by NSXTASY. You need to drive the car a while (2-5,000 miles) in different conditions to have the experience yourself before you spend a dime on mods. I have done no mods yet, but I am considering adding the sway bars, because I do like want less body lean in the corners. I do not want suspension changes, because I don't need more speed in the corners: the car is already so fast in the corners that it's scary (to me). (I don't wnat to go any faster than I already do on public roads.)
Re warranty: When I got my NSX in April I called Escondido Acura, who did offer a warrantee, which required thier inspection first, but I don't remember how much $ they wanted. Maybe give them a call. I didn't get the warranty after realizing (from reading NSX Prime FAQ) that I probably will not need the warranty, because 1) it's got the realiablity of a Honda, and 2) I do not abuse my car. For me, I'm gambling that the warranty $ would be a waste. So far, I'm right.
BTW, where do you reside in S. Cal?
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NSXY
95 NSX-T, 5 sp, Red/Tan, Stock, except Dunlaptya SP9000s