I sent my older GTI 2500 detector to Garrett to have it checked over and re-calibrated to accomodate the new 9.5 coil. When I received it, they had kept my old 8.5, white, coil and sent me the new 9.5 black spider coil and new stem. The modification cost was very reasonable and much less than if I would have bought the new coil. I feel that their service was excellent. If anyone has had some hunting time with the new coil, what are your opinions on it's performance?