The standard GTS 4.0 is 20mm lower than a normal Cayman but if you opt for Porsche Active Suspension Management (PASM) incl. ride height lowered it means that the car is actually 10mm higher than the standard GTS 4.0 and not, as it implies, 10mm lower.
The option says For slightly added driving comfort and ground clearance, the standard “PASM sports suspension (20 mm lowered”) is replaced with “Porsche Active Suspension Management (PASM) incl. ride height lowered by 10 mm” for no extra charge. With this option the ride height of the GTS 4.0 models rises compared to the standard set-up.
Did you go for the option on yours or not ?