[nutron]

I would have though 12.5 was a rather high a/f ratio. The leaner the mix, the hotter the engine will run. w/i will bring down the temps but your still playing with fire. If you use water/methanol you will be adding more fuel as well and this will help with power and bring down the a/f ratio so you could add more air. What you need to be careful of is the cylinder pressure. Adding water will increase the cylinder pressure because the water will turn to steam and expand rapidly. If you turn up the boost and use w/i you might over load it. Better to keep the boost where it is and add the water/methanol at that level.