I had one a couple of cars back, bought it standard with the intention of selling it on. I sold my AE86 so was "forced" to drive the MX5..lol. To say i was impressed was a understatment it handled like nothing i'd driven before, the only thing i could compare it to was the sort of feeling you get when your go-karting.
After a few weeks i came across a set of TEIN HA's and chucked them on with a couple of lower chassis braces and a strut top brace. Fook me the car was amazing i had so much fun it was unreal.
Again i then sourced a Tanabe Exhaust and chucked a HKS intake on it which helped it a bit. The biggest problem i had with the car was the lack of tourque to do anything dangerous in the car you had to attack stuff at high speed cos the wasn't enough power to keep things spining.
My suggestions are in no perticular order
1. Decent suspension + Lower chassis braces
2. LSD (if i had one i'd of probably still have the car now)
3. Power more the better turbo/supercharge readily availible
4. Cage cos i had a few scary moments where i though it was gonna go over!
5. Aero cos you gotta admit they look a bit :dermal:
6. Decent offset rims 14 or 15" but wide
Im at the stage again were im looking for another car and have narrowed it down to 2 choices a R32 GTS or another MX5 but a proper one cos i gotta admit even though everyone called me a puff i loved the car.
Adam