I have the pins on both sides yes, the fact that there are more than just one path for the liquid to take, reducing the flow-resistance of the block considerably, is what accounts for the apparent "not so bad flow" ....
also, the fact that the liquid spend a very short amount of time in the block, makes for awesome replacement rates, I.E.. the liquid does not have to follow a long and winding road to be able to get out again, it takes the first available path of least resistance and then it's on its way back to the radiator, making space for new cool liquid to enter....
I'm kidding.... I'm using magic cheat codes to get the flow up...
