Sooo basically i've had the dreaded situation where a spark plug has worked it's self loose causing it to strip the head of the threads..
Has anyone ever encountered this problem?
The car was serviced 5 months ago at a Local Garage they replaced the Plugs but with Standard Denso plugs instead of Iridium plus which was asked!!

I am running -15% Pulleys on the car

What are my best steps now? Has anyone had any experience with Heli-coiling the head in situ? (without removing the head)

What sort of price should i be looking at for someone to do this?

Or what sort of price should i be looking at for a new head + Fitting?
Hope you Guys can help me!

Many Thanks Max

Hi ya

Have a look at this link wurth do kits to repair them, I have done the job with out taking to much apart. Plenty or grease to catch the swarf and a hover and thin hose to clean out cylinder just Incase

https://shoponline.wurthusa.com/wurthusa/servlet/CyberVendor/category/C4322218/catalog/

Hope this helps just take your time do not rush

Just a note when i fit new plugs i check torque them every weekend till they do not move then every three months, minis do seem to have this problem with lose of torque

http://www.mini2.com/forum/first-generation-faults-fixes/187822-spark-plug-popped-out-stripped-threads-help.html#post3809243

TIME-SERT Spark Plug Thread Repair - YouTube

Denso plugs, these have a bad habit of doing this.

I've always removed a head to fix this.

Is this even physically possible? Are you sure you didn't cross-thread and strip the threads when you were putting the plugs in? It's a pretty common mistake.

Spark plugs can work loose over long service intervals and then with the force of piston compression wobble in the threads until they pop out taking the remaining threads with them.

cut a new hole (M18) with a cutter/tap. Then thread in an insert. Then put in the same size plug -- very easy to do!