Originally Posted by RS Specialist

rods are different there is a "light" and a "heavy" rod,difference being the counter weight above the little end,so make sure you have a match set,also the 4wd pistons have a different size bowl in the piston which will effect yout compression ratio,persoanly I what ever pistons you use gets them decked and bowled oout the decking will avoid any pistion to valve contact which all cossy engines had even from new,so you will get even more conatact as your head will have been skimmed at some point