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19 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 19 Reviews
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Filter Reviews:
    United Kingdom United Kingdom
    Great spark plugs

    Ordered these last year, just ordered again ready for service, excellent quality.

    Niall B.
    United Kingdom United Kingdom
    Quality spark plugs

    Great delivery and service, accurately pre-gapped too. Purchased in preparation for further power mods

    Daniel S.
    United Kingdom United Kingdom
    Spark plugs

    Have made a great difference to the car.feels smother.Delivey nice and quick.