EU customers, please read before purchasing

Important Info

Search our store

29 reviews


Iridium Spark Plug Set [Mk3 / Mk4 Focus ST]

EcoBoost engines running substantially higher boost pressure or increased levels of tuning compared to the OE power output can experience reduced spark plug life resulting in lower engine performance, misfires and rough idle.

Increased wear is typically seen in the form of increased spark plug gap and degradation of the electrode. Using spark plugs that are optimised for increased power ensures maximum performance.

Extensive in-market validation at extreme boost / cylinder pressures was undertaken to ensure optimal performance was achieved, whilst also making sure  reliability and drivability wasn't compromised in colder ambients.

Each set is supplied pre-gapped by mountune to optimise the setting and allow for easier end-user installation. 

The NGK LTR71X-II is one step colder than the original spark plug.

Focus ST 2012-2018
Focus ST 2019-current
  • Smoother acceleration
  • Perfect for high boost applications
  • Supplied pre-gapped by mountune

Please note:Supplied in a pack of 4 plugs.

Customer Reviews
5.0 Based on 29 Reviews
Write a Review Ask a Question

Thank you for submitting a review!

Your input is very much appreciated. Share it with your friends so they can enjoy it too!

Filter Reviews:
    Benjamin C.
    United Kingdom United Kingdom
    Spark plugs

    Cars running stage 1 these plugs would 100% recommend

    Wolfgang S.
    Germany Germany
    Perfect service

    It was perfect, very fast shipment! Thank you

    Paul H.
    United Kingdom United Kingdom
    ST250 iridium plugs

    Brilliant comms and plugs pre-gapped Top class

    mountune Iridium Spark Plug Set [Mk3 / Mk4 Focus ST] Review