What about ditching the air-to-water for an FMIC? I'm sure there's some table out there stating for every 10* in temp drop that it equates into X in HP increase. I'm assuming it'd create a little lag considering how the intake system is designed in these vs normal engines, but it might be worth the gains. I'm still searching the forums for actual experiences.
http://www.bimmian.com/AIC/70/