MX5 NA standard 063 battery set up with G19 Engineering clamp. Usually a 5yrs warranty on battery compared to 1yr on the Panasonic.
Bosch 063 battery (Yuasa are also recommended) Bosch Car Battery S5001 | Battery Group
Vent Pipe Battery Vent Tube / Vent Pipe | Accessories | Car Batteries | Batteries by Vehicle | Battery Group
Battery Clamp G19 Engineering - Battery Conversion Kits
T-piece Plastic Hose Joiner Tee - Silicone Vacuum T-Piece Elbow Pipe Boost Gauge Tap | eBay
Battery Mat The Original Acid Neutralising Battery Mat. Absorbs acid & dampens vibration | eBay
Isolator Discarnect Car Battery Disconnect Isolator Cut-Off Switch + fuselink | eBay
TOTAL price for this entire list of components is about the same price as the expensive Panasonic battery.