ive rode in both types of motors too dumbass... i do know what im talking about.. the only good thing about gsr heads is that they have a smaller combustion chamber.... other than that there shit... u said 900 for a pr-3 head..... i said port and polish a b16 and duel springs u got urself pretty much a type-r head... wich is way better than a gsr head... i know... ive done tons and tons of research before i started my build wich i have close to 4500 into it right now... so ya...