I'd say no more than 6 maximum. You also need to ensure that there are enough basking sites, hides and water access for all of the animals to live comfortably without competing for resources. It is important to remember that you should only house 1 male to an enclosure though, otherwise they'll fight. Also, any infectious pathogens such as bacterial infections are likely to spread like crazy in a large colony, so be warned.
Thanks peeps, i do have another male but still smaller than the others and in a diffrent viv, so i might pop him in when he is big enough to stick up for himself, but i think i might get a couple more yay, females that is,