I don't know how hot the ECU gets. But I see no reason why you couldn't mount it in a box with a breather. It is mounted under the carpet on the floor board. So Kia obviously didn't have issues with heat-related failures due to lack of air circulation. I suppose the floor panel, being metal, could act as a heat-sink to pull heat away from the electronics. But you could get the same effect by using a sealed metal box. The big hurdle to jump is waterproofing the harness entry. And you won't be able to relocate the box without extending the harness - no easy job, by any means. If you were to put it in a sealed box and manage to seal the harness entry point, I'd recommend a breather, as you mentioned, possibly with a small fan to circulate air. I'd be interested in seeing how you did it, if give it a go... <img src="/forums/images/graemlins/cheers.gif" alt="" />