Maruha Long Stroke Suspension Top Mount · NA / NB Miata
Maruha's own-design solution to one of the most persistent complaints with lowered Miatas — the harsh, bouncy ride that results from insufficient suspension travel after fitting springs or coilovers. By adding 20mm of stroke to the OEM-style top mount, the shock can move through its full designed range even at reduced ride height, restoring the damping behaviour the spring rate was calibrated for.
Technical Details (from Maruha Motors Japan):

Adds 20mm of rear shock stroke vs. standard NB upper mount geometry
OEM-style stamped steel top hat — NB specification
Compatible with aftermarket coilovers accepting OEM NB top mounts (e.g. Tein Basic)
NA Miata installation: requires NB bushings and hardware (not included)
NB Miata: reuse OEM factory bushings — direct fit
Included as standard in Maruha BC Damper coilover kits
Also sold standalone for owners upgrading existing coilover setups

Fitment: NA Miata 1990–1997 (requires NB hardware) · NB Miata 1998–2005 (direct fit).
Made in Japan. Authorized Maruha import by Chikara Motorsports — North America's only official Maruha dealer.