I’m personnaly in love with the Aero Master B-Wave kits.
RS13, PS13, S14 and RX7 FC Aero Master kits are for me some of the finest kits of the 90’s era.
The ability to change front and rear headlights / headlight panels would also be a great add.
For example : fixed headlight on RS13, RX7 FC / FD, MX5 NA. (gain of around 10kg of weight)
Some kits also change the rear headlights (for example Type X kit on 180SX, Garage Vary rear panel on MX5 NA)