Not really, I think I have a pair of the cross hair lights in the shed from one of my old MKII's. THe only mods I'm looking at for the MX5 are a front lip and maybe some -35mm springs. Other than that it's awesome. THings that wear out will be replaced with upgraded items though. If bushes need changing it'll get poly bushed, if the manifold starts leaking it'll get a stainless 4 branch etc etc. THe only other thing I might get is a hardtop with a heated rear window for the coldest parts of winter but they're pricey at £300 for a tatty one or more than I paid for the car for a new one!
Nick