Telemetry rate issues.

In arducopter 3.6.x I was able to set a rate for telemetry transmition higher then the official 10Hz by changing parameter SR1_EXTRA1. I’m usually working with a rate of 50 Hz and setting SR1_EXTRA1 to 50 allowed it with no issues. As of Arducopter 4.0 this is no longer the case. telemetry transmition rate is limited to maximum 10Hz no matter what value I set to SR1_EXTRA1. Is there a way to allow for a faster telemetry rate under Arducopter 4.x?