Flow Designs - Focus ST MK3.5 Rear Diffuser


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Please Note: Pricing on our site is pricing for this one individual part picked up at our shop. Please contact us if planning on buying more than one FlowDesigns product as we will be able to offer discounts on multiple Flow products.

Please Note: Flow Designs products do not ship for free, please contact us so we can get you a custom shipping quote if you're not picking up. If you order first we will email you a shipping quote within 48hrs.

Make your MK3.5 Focus ST unique with the Flow Designs splitter set, complete with front & side splitters, rear adjustable diffuser set, rear spats& adjustable accessories. Flow Designs splitters are the most durable on the market, with guaranteed fitment to your MK3.5 FocusST & easy installation.


Each diffuser fin is reversible giving you 2 style choices to choose from. Diffuser fins are also slotted which gives you the flexibility to set the depth. Pull them out for an aggressive look or push them in to keep it neat and tighten when done.

Diffuser fin profiles can be set before or after installation, adjustment can be done on the car by loosening a few fasteners (refer to fitting diagram).

This 8-piece set includes a pair of adjustable diffuser winglets and a pair of spats for everything to mount to.
Everything is pre-drilled and there is no need to remove the rear bumper for installation, only basic tools and knowledge is required.

Dont want the fins? Spat can be sold own it'sHERE


  • 4 x Rear Adjustable & reversible rear diffuser fins (Set)
  • Rear Adjustable Rear Diffuser Winglets (Left + Right)
  • Rear Spats (Pair)
  • 2 Flow Designs Stickers
  • Fitting kit


  • 10mm thick polyethylene composite, bevelled edges


  • Hand polished satin black

Why do we use Polyethylene Composite for Flow Designs Splitters?

Strong, impact resistant, doesn't corrode or chip, and has excellent abrasion resistance (say from scraping on driveways and road all the time?)

Carbon Fibre is better, isnt it?

As strong and light as Carbon fiber is, it CRACKS on impact or when under load and/or stress. Clearcoat will eventually fade & crack and become undesirable.

Installation Instructions


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