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Auxiliary Cold Air Intake (ACAI) [Mk8 Fiesta ST]

The mountune Auxiliary Cold Air Intake (ACAI) offers multiple airflow and aesthetic enhancements for owners of Mk8 Fiesta ST.

The all-aluminium ACAI assembly replaces the plastic air guide, which can either brake or sag behind the grille and improves upon the complex pathway that the air normally enters the induction system, with a pair of flow-optimised deflector scoops.

This ensures you get more cold air going into your OE intake crossover pipe, whilst blocking a minimal surface area of the radiator and causing a negligible affect on the radiators performance, unlike some larger standalone scoops.

In addition, we’ve then added an auxiliary air intake which can be used for multiple purposes; either with the supplied air feed hose and aluminium joiner to neatly connect with a mountune induction kit lower shanon hose (which provides an enhanced cold air feed from the front of the car) or alternatively, can be used to channel cold air directly onto our forthcoming inner-wing-mounted oil cooler kit.

Engineered to work in harmony with the mountune intercooler (not compatible with full-height intercoolers), the ACAI upgrade allows for enhanced airflow and cooling in multiple configurations, regardless of the induction system you are using.

Take advantage of our cooler combo and save 10% on both the ACAI and our high performance intercooler when purchased at the same time. Just use code gowiththeflow

Go with the flow

Not only does the ACAI give you two carefully flow-optimised cold air feeds to the OE airbox feed, we've also added an auxiliary scoop which can be used to feed either our forthcoming oil cooler kit, or joined to the porous lower hose supplied as part of the mountune induction kit setup, or even directed to a third-party intake.

Nothing else offers the same level of enhanced cold air optimisation, whilst crucially not inhibiting airflow to the radiator #gowiththeflow

Airflow, where you need it

The ACAI auxiliary scoop can be easily connected to an existing Shanon hose (found in all current mountune induction kits and our forthcoming open cone filter kit) with the supplied hose and aluminium joiner as shown, or to feed a third-party induction kit, or to directly channel cold air onto our forthcoming inner-wing-mounted oil cooler kit.

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5.0 Based on 8 Reviews
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    France France
    Air secondary

    Super product, perfect fit and superb quality Complementary with air box mountune very cool

    mountune Auxiliary Cold Air Intake (ACAI) [Mk8 Fiesta ST] Review
    Martijn O.
    Netherlands Netherlands
    Great product

    Great looking product! Taking the front bumper off was a bit annoying, but the rest was easy. Make sure that you get an extra hose clip as well since you’ll need 3 instead of the 2 that are included. The new hose also could have been a tiny bit longer, it worked on my side, but received questions from others how I was able to make it fit.


    Thanks for the feedback Martijn. The kit does include three jubilee clips as standard, so apologies if you were one short - please contact if you still need one. The two porous hose sections do need to be routed carefully as per the image shown on the product page (for any other customers reading this) and connected in the order shown in the fitting guide, but it does provide a neat solution when routed as suggested.

    Shaun M.
    United Kingdom United Kingdom
    Cold air guide

    No problems, but tricky taking the whole front bumper off. Nice for my extra air box pipe to have a proper home. Would Recommend fitting a better inter-cooler at the same time as it’s not much extra work doing both. Get new plastic clips before starting job as you will break some.