... i run a gen 3 in my gen 2 3s-gte.
the gen 3 toyota gasket is metal and its the same as the TRD gen 2 one....
as for boost, it's up to you, but i wouldn't bother with more than 15psi.... 17 if you really want the numbers... but 15 seems to be a nice balance for the ct26.... should see around 150rwkw.