What is the suitable head for H22a vtec? Is there any increase in power when using H23a Blue Top? Or any other that has been tried/swapped? Need help.

 

Euro R or Type S head would be the only upgrade. And to be honest with you. The gains are not in the head castings themselves. It's the pistons, cams and intake manifolds that you should be looking into. Cheaper to swap out parts than a complete head.