Maxton Design Street PRO Rear Side Splitters with Flaps for Subaru Impreza WRX STI Mk3 Facelift
Give your STI a sharper, lower look with functional styling that lasts. These Street PRO rear side splitters with flaps finish the rear bumper edges, helping smooth airflow along the sides while adding a purposeful, track-inspired detail.
Designed for a precise fit on the Subaru Impreza WRX STI Mk3 Facelift 2011-2014. Please use our vehicle lookup to confirm compatibility, or check the Vehicle Fitment tab for full details.
Made from 10 mm ABS plastic, they are tough, impact resistant and built for daily use. A UV-protective coating helps prevent fading, and the material stands up to temperature and weather changes. Each part arrives with a protective film on the surface to help prevent marks before fitting.
Choose a clean Matte Black finish, or Matte Black with a subtle red core for a bolder edge. No painting is required. If you choose to paint, use a primer first.
Supplied as a complete set with rear side splitters, flaps and a mounting kit for a secure install. Professional fitting is recommended to ensure alignment and durability.
TUV MATERIALGUTACHTEN certified for material quality. Parts are authenticity-labelled.
Choosing a Kit
Our vehicle registration lookup system cannot detect factory trim level. It is important for customers to check the specification of their own vehicle against the product description, and if their vehicle has an existing sports trim level, body kit or factory enhancement that may cause it to look different from other similar models.
For example: Volkswagen R-Line, BMW M-Power/M-Pack, Audi S-Line, Ford ST-Line, Merc AMG-Line, Seat FR.
These kits will not fit models that don't meet these specifications.
Returns
Purchased the incorrect kit for your vehicle? Or not sure you like the surface finish when it arrives? No problem!
Maxton Design products are eligible for return if the product has not been fitted, drilled, modified or damaged in any other way and still has the protective factory film intact. Unfortunately, there are no exceptions, this applies to fully removed and partially removed films.
Products with a protective film in place are clearly marked with this sticker, if you believe there to be an issue with the product but you can't tell without removing the film, please contact our support team directly for assistance.

DO NOT REMOVE THE FACTORY FILM UNTIL YOU'VE LINED IT UP, AND YOU'RE READY TO FIT THE PART.
See our Terms & Conditions for more information.
Installation & Fitting
Instructions & Guides
Maxton Design provide either an online reference (below) or printed instructions with their products, we can't stress enough how important it is to follow these guidelines. Not only does this create a safe, aesthetically well fitted product, but it increases the longevity and lifespan of the kit.
Neither Progressive Parts nor Maxton Design will be able to provide and support or warranty for products fitted incorrectly. For example, front splitters require the front bumper to be removed, without doing so the bolts will be incorrectly positioned and may not be able to cope with the down-force exerted on it. Straying from the guidelines in this manner must be done so at the owners risk.
Fibreglass & "Non-Prepped" Products
By adding these products to your basket you are agreeing to the below statement.
All Maxton Design Fibreglass products including certain bumpers, spoilers, spoiler extensions and skirts will require “prep” before installing.
These are not a simple 'ready to fit' modification. In transit, the items may get chipped or marked and as such prior to painting it is important you understand that the parts may require filling, sanding and repairing (defined "prep") prior to paint being applied, which can be undertaken by any reputable body shop at minimal cost.
Return requests based on not anticipating the definition above are not accepted, please be aware you have agreed to this statement and the definition of “prep” work required prior to purchasing.
Product images shown for sale often indicate a finished product, the colour shown on the vehicle is for illustration purposes.
Fitting Manuals
Please note, Maxton Design products are only available for UK shipping.
Including Northern Ireland, Scottish Highlands and Channel Isles. Delivery fees apply.





