of course you can change the baudrate to the other defined baudrates but it's not recommended for other UARTs than the external UART (UART3).
It is also possible to change the baudrates of the GPRS Modem by using AT-Commands. For detailed information about that please have a look at the documentation of the Modem on the product CD (AT_Command_Interface_Guide.pdf).
Please note that changing the bauderates may make the communication between the modem and the controller impossible if the baudrates and there is no easy way to reset the settings of the modem. So if you'll change the settings you do that on you own risk.
Thanks for your quick response!
I have a question about "there is no easy way to reset the settings of the modem".
In order to speed up CAN data transfer rate to GPRS-Modem througth UART1. If i will take the plunge then failure, can i recovery/reset the factory settings by myself? or must return device to original factory?