thinking of going with gt40ps..what do you think??

Like was said, you need an intake to go along with them. With a little portwork they are a surprisingly good head. If your staying NA you might want to have them milled as well.
 
I agree with everyone else. They are a good head if you are on a budget but there are a lot better heads out there. Have you tried looking for some used trick flow or edelbrock heads? I would say AFR but I doub't anyone has a used set for sale.