yeah and i've done some reasearch and the is4 heads from intense and the aluminum ones flow almost the same. The only difference is the exh port on the zzp head flows less than the one on the is4 head... and for getting the exact same head (same valves ect) that intense has i'll do my own port work to make them flow just as good(just bought some stock ported heads with bigger valves). even if i dont i got them for almost 2000.00 cheaper...It is not worth it to me to get aluminum heads and not gain much hp at all and waste 2000 dollars.