For now, I'll just keep the stock water box as it is. Surprisingly, it works really well. I was able to get the plumbing to and from the pipe without any kinks or rubbing. The ID of the inlet and outlet of the box is 1/2" smaller than the new exhaust tube that I plumbed in. But, that doesn't appear to hurt performance - Yet. This motor is a stock 750 small pin, with the only mods being a 46mm SBN and the Factory pipe. When I go to a bigger motor, I'll rethink the waterbox.looking good. What the plans for the water box? Are you going to make the inlet & exhaust bigger.