I am not sure you will be able to go faster just by adding this board. A lot depends on your mechanical setup and how much power your steppers have! Also, have you maxed out just how fast you can go in the configuration. Possibly you have your max speeds set to low? Or can you change the feed rate in your g-code program?
I would look at the last thing first! If you are telling it to go slow in the g-code file, it will still go slow as you have to change your configuration for using the multiplyer board. Remember it you multiply steps by 10, you have to change your steps/unit by X/10 or it will move 10x as far as you command. Therefore, no speed change!