Search our store

24 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 24 Reviews
Write a Review Ask a Question
  • Reviews
  • Questions

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:
    United Kingdom United Kingdom
    Iridium Spark Plug Set

    Very fast dispatch from the Mountune team. Already gapped so ready for "plug n play" should go well with the MR300 pack I am making up, just waiting for the intercooler which is on it's way.

    Perminderpal D.
    United Kingdom United Kingdom
    Iridium spark plug set ford st

    Very good quality and pre gapped which save us novices fiddling about with a feelers gauge . So thank you .

    daniel v.
    Netherlands Netherlands
    0erfect for my focus St

    glad that they where pregapped. the engine runs smoother now! these spark plugs are an important step before i let it run on stage 2

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