If it were me I would shoot 100 gr heads. But there is nothing stopping you from going to a 125 gr or heavier. A rule of thumb is you loose 1 fps per each 5 grain increase. So going from a 100 to a 125 you will loose around 5 fps but will have increase penetration. The heavier head will also make the shaft behave as a slightly weaker spine which wont hurt your set up one bit.