Recently I had my car RR to check mixtures - it was rich (after me worrying it was lean in typical coupe paranoia )

Anyway I have the problem in daily use of it fouling plugs.

I am running the spec cold and hard plugs for the Evo chip. They are NGK B8EGV's

Can I run a heat range hotter to try to keep them clear and get away with it for traffic?

Realise if i was track daying it then the cooler plugs would be great but for idling in traffic maybe something hotter

If your just spending most of your time sat in traffic then your probably better off with a set of standard plugs, uprated plugs will never get to their self cleaning temperature.

But if you go to standard plugs and decide to use some boost, you will just blow the spark out and not go anywhere, hence the need for the colder plugs