[QUOTE=The_Denv;88507]Well I don't know what the increment should be, but if you increase it by 1dBi each time until it doesn't work; you will find your answer.

iwconfig rausb0 txpower 10
Then increase it by 1dBi each time:
iwconfig rausb0 txpower 11
It was ‘rate’ that I was interested in but I gave ‘txpower’ a go and ‘iwconfig’ said ‘Operation not supported’ Tried increments of ‘1M’ with ‘rate’ using ‘aireplay-ng -9 rausb0’. For what it is worth, found 1, 2 and 5 worked well, 3 & 4 and all above 5 with the exception 9 failed to inject. 9 worked some of the time.