8 to 10psi @ the most anymore than that your going to be on the side of the road wishing you hadnt messed with the boost settings.. I had a crvtec et up with rods and pistons and ran 16psi all the time for about a year then cracked all 4 sleeves. If your going to repalce the rods get some sleeves, spend the extra $ and have fun not a headache.