as far as inexpensive swaps go, you can always put the K20A2 head on top of the K20A3 block.

other than that, the K24 from a CR-V or 4 cylinder accord would work as well. they both have 160hp, but more torque which isnt a bad thing at all.

stock motor can handle 12psi safely. although i have seen stock K20A3's that have taken more than that.

honestly, i would spend a little extra money and look into a revhard kit or something similar as there are more gains to be had over the greddy kit, IMO.