I've got my PCM laying between the FWI and the coolant recovery tank. I don't think my MPG went down at all. What I don't like is that the PCM is getting all the heat from the coolant tank. I've put some rubber sheets and hoses as spacers in between, but it still gets hot. What can I use as a heat shield or is there a write up on how to make a home made heat shield here? I've looked around but haven't found any.