... should I plug the heater hoses, or connect them together?

The car runs fine with the lines plugged, but a couple days ago it was really hot weather, and instead of running at 180deg, it was running at 220deg!

This is for the Prelude-powered Mini which of course has a different cooling layout, but as far as the engine's concerned, it's no different than a Prelude.

I know there are a number of things that could be contributing to this but thought I'd start with the easy stuff.

 

shouldn't be an issue, mine are plugged as well.