That is a good question. Looking at images of the stock 4G63 cast pistons, they have reliefs for the valves so I am going to say...no. BUT the stock 4G63 pistons run a higher compression ratio of 9:1 compared to the 8.5:1 of the G63B SOHC engines (this may be the loophole that will allow the necessary valve clearance to swap the heads). So I can't be sure I looked at the DSM tuners site and this subject was touched on albeit on the 2.4 and no mention was made of swapping pistons - http://www.dsmtuners.com/threads/can...-block.100056/