please read.. timing question

my 1992 2.9L ranger's timing was at 25 degrees. i put it at ten degrees which is what it is supposed to be set at.
at 25 degrees the truck had alot of power. i could easily peal out from a stop light. now i dont have as much.. and if i get significantly better mpg im fine with that.
my question is is how much better mpg, if any am i looking at..
this wont hurt my mpg will it? like maybe im not getting a complete fuel burn..
i hope yall can help.

