XYZ Racing Super Sport Coilovers — Maserati BITURBO SI φ52 welding (PCD: 4X98) 1986-1991

The Biturbo SI’s turbo lag has a nasty second act: once both blowers spool up together, torque arrives in a lump and shoves weight rearward through a chassis and dampers that were never firm enough to catch it cleanly. Body roll and a soft, wallowy rear end under that surge are the defining complaint on any Biturbo SI that’s still running its original suspension nearly forty years on.

XYZ Racing’s Super Sport coilover is built for exactly this kind of car – a fast-road and weekend-track setup rather than a full race rig, which suits a Biturbo SI owner who wants sharper responses without turning the car into something unusable on the school run. Ride height and damping are both adjustable, so you can correct decades of sag and tune out the wallow in one pass.

What this coilover does for your 1986-1991 Maserati Biturbo SI

Most surviving Biturbo SIs are sitting lower than Maserati intended, simply from age – tired factory springs settle, and that changes the geometry the engineers designed around. Ride height adjustment on this coilover lets you put the car back where it should sit, or drop it further for a track day, without guessing. The 36-way damping adjustment is the more important change for this specific car: with a manual dial you can firm up compression to control that rear-end squat under boost surge, then back it off again for a motorway run the same weekend. Monotube construction responds faster to the sudden load changes a twin-turbo delivery creates than the twin-tube dampers Maserati fitted from the factory, so the transition from turbo lag to full boost feels controlled at the axle rather than absorbed by body roll.

About the Super Sport coilover

XYZ Racing’s Super Sport line is built to take the harshness out of rough road surfaces without dulling response, which is the balance a Biturbo SI needs given how uneven the ride quality has become on cars running original, ageing dampers. Ride height is adjustable independently of the damping, so lowering the car for a track outing doesn’t force a compromise on how it settles on broken tarmac. The 36-way adjustment range covers a wide spread of conditions – motorway cruising, B-road driving, and circuit laps – by letting the driver dial the damper firmer or softer rather than living with one fixed compromise. It’s designed as a single set-up that does daily driving and weekend track sessions without needing to be swapped between the two.

Fitment for the Maserati Biturbo SI (1986-1991)

This kit is built for the Biturbo SI, chassis code MS03, covering the full 1986 to 1991 production run. It’s specified with the φ52 welding-type top mount rather than a bolt-in unit, so fitment involves welding the mount to the shock tower – factor that into your install plan. PCD is 4×98, matching the Biturbo SI’s original hub pattern.

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Spec your damping and ride height for the Biturbo SI’s turbo-surge handling – configure yours below.