i have same prob atm due to running something like a 10t in a 14 t lrp pro reverse ESC. im moving to a 19t soon so im gonna keep mine but i would suggest one if you got around £60, but that aint cheap. soo erm hang ill have a look for you.
http://cgi.ebay.co.uk/Mtroniks-Viper...QQcmdZViewItem
http://cgi.ebay.co.uk/Mtroniks-Sonik...QQcmdZViewItem
http://cgi.ebay.co.uk/V16-Digital-Sp...QQcmdZViewItem