Can I upgrade my GNS400/500 series GPS/Nav/Comm to have HTAWS enablement?
No, you cannot directly upgrade a GNS400/500 to HTAWS. You must first upgrade the unit to WAAS before adding HTAWS capability.
The total (approx.) cost to upgrade a GNS400/500 series unit to have HTAWS (WAAS first, then HTAWS) is $15,000 List.