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I decided I might do a plug change today. The ones I pulled out are NGKR BKR6E. Not sure if I should put a new set in the same as I pulled out or not.

No idea on plug reading so any thoughts would be appreciated. These have done probably 20,000klm

Looks to be running rich, but the slightly colder NGK plug you're already running (NGK BKR6E) is the recommended forced induction one for country driving, with NGK BKR5E for city driving. However, if you've only been using it around town & on short runs recently that colour is not really surprising. Also, is it currently running on the safe tune, & you mentioned occasional high idle during & after NT trip?
Btw, some also use NGK BKR7E for FI:
Dann's advice:

NitroDann wrote:The best spark plugs are oldschool plain jane copper ones.
You want to go colder as you run high BMEP.
You can gap down but you will get a less complete burn.

https://mx5cartalk.com/forum/viewtopic.php?t=59779

Interesting, I just added forced induction to Munich car and currently have bkr7e with whatever gap they came with and am going to put bkr6e in as I read these are the most common path for FI

The appropriate heat range is going to depend on how hard you run the engine.

I generally fit a 7 but most of my customers are driving very hard regularly.

A 6 is suited to bigger power, but used sparingly.

Dann

thanks, will stick to the heat range 6. the high idle issue picked up in the territory has subsided.

These will help. Perfect with up to 20psi with 7s so far. Talk to Brendan Beavis for more info.