ST Suspension offers several coilover ranges that share the same basic goal, adjustable ride height, but differ significantly in damping adjustment and top-mount hardware. Choosing between ST X, XA, XTA and XTA plus 3 should therefore be based on how much setup control you actually need.
ST X: height adjustment with fixed damping
ST X is the simplest complete coilover option in the range. Ride height is adjustable, while the damping is fixed by the manufacturer for the application. It suits drivers who want a lower, more controlled chassis without adding damping controls they may never use.
ST XA: height and rebound adjustment
ST XA adds rebound-damping adjustment. That gives the installer or driver more control over how the suspension settles after a bump or weight transfer. It is useful for a fast-road car where wheel and tyre changes, road quality and driving style can make a fixed setup feel too soft or too controlled.
ST XTA: adjustable damping and top mounts
XTA adds application-specific adjustable top mounts alongside damping and ride-height adjustment. Where the top mount allows camber adjustment, this can be particularly useful on cars that need more front negative camber for fast-road or track use.
Top-mount design is vehicle-specific, so do not assume every XTA kit provides the same adjustment range or hardware.
ST XTA plus 3: three-way adjustment
XTA plus 3 provides separate rebound, low-speed compression and high-speed compression adjustment on the relevant applications. That gives considerably more setup control, but it also requires a more structured approach to testing.
For a track car, record the baseline settings and tyre pressures, change one damping control at a time and assess the car under repeatable conditions. More clicks are not automatically more performance.
Which ST coilover is best for road use?
For a road-biased car, ST X or XA is often the logical starting point. X offers a straightforward matched package; XA is more suitable when you want to fine-tune rebound response. XTA becomes relevant when top-mount adjustment is useful, while XTA plus 3 makes most sense when you genuinely intend to develop the setup.
Which ST coilover is best for track days?
Track use increases the value of damping and alignment adjustment, but the correct kit still depends on the car. Tyre grip, spring rate, brake setup, alignment and driver experience all affect whether additional damper controls are useful.
For BMW F87 M2 and M2 Competition, compare the ST XTA plus 3 application. For F80 M3 and F82/F83 M4, see the ST XTA Plus kit.
What about BMW EDC?
Check whether the vehicle has factory electronic dampers and how the selected ST kit addresses them. If a passive coilover replaces an electronically controlled damper, the car may require the relevant cancellation solution. A cancellation module prevents an electronic fault; it does not make a passive damper electronically adjustable.
ST Suspension for M135i, M140i, M235i and M240i
F2X and related platforms have multiple ST options. Compare the ST XA application with the more adjustable ST XTA plus 3 application. Confirm drivetrain, body style and original suspension before ordering.
ST Suspension for Porsche 987
Porsche Boxster and Cayman 987 owners can compare ST X and ST XA. The key difference is that XA adds rebound adjustment. The precise derivative and factory suspension still need to match the product application.
ST coilover FAQs
Are ST coilovers made by KW?
ST Suspension is part of KW Automotive. The ranges are positioned differently, so a product should still be chosen by its own specification rather than assuming it is identical to a particular KW kit.
Do I need an alignment after fitting ST coilovers?
Yes. Set the final ride height, check clearance and suspension travel, then have the geometry measured and adjusted.
Does lowering more improve handling?
Not automatically. Excessive lowering can reduce usable suspension travel and create geometry or clearance problems. Choose ride height around the complete chassis setup.
Browse the full ST Suspension range at Nineteen72 Performance.
