9900 FPM Vertical Speed limitation.

I'm in the process of writing an XML routine for a high performance aircraft but find when using the command:

if{ @VSIOffset 1200 + (>K:AP_VS_VAR_SET_ENGLISH) } the @VSIOffset macro result is a computed value up to 20,000 meaning I need the aircraft to climb or dive at that rate, for a short time.

The maximum vertical rate the AP system will take is 9900 feet per minute in either direction, is there somewhere I can increase this value, scratched around in most common places and can't find it.

Thank you in advance.