Why the Best Aftermarket Body Kits Are Made From Polyurethane — And Why STILLEN Has Perfected the Process
You've heard that STILLEN designs, engineers, and manufactures its products right here in the USA. In this piece, we're going behind the scenes to show you exactly what that looks like — following the production process of our polyurethane body styling line from initial concept to finished part.
If you've ever wondered what makes a STILLEN polyurethane body kit different from the fiberglass or cheap urethane knockoffs cluttering the aftermarket, this is where that story starts.
It Starts In-House — Every Time
Every STILLEN body styling product — front splitters, rear diffusers, side skirts, roof spoilers, trunk spoilers — originates in-house. Our design team develops the concept, and our craftsmen at our Costa Mesa, California modeling shop bring it into physical form. First article prototypes are then scrutinized by the entire STILLEN staff before anything goes near a production mold. The goal is simple: if it doesn't fit right, if it doesn't look right, if it doesn't perform right, it doesn't ship.
Why Polyurethane? Because Fiberglass Breaks.
This is the question we get most often, and the answer is straightforward. STILLEN's proprietary polyurethane blend is the result of years of formulation refinement to hit a very specific material sweet spot: rigid enough to hold its shape under aerodynamic loads, flexible enough to absorb road impacts without cracking or shattering.
Fiberglass body kits look great in photos — until a road hazard, a bump, or even temperature stress causes them to crack or shatter. Carbon fiber has similar brittleness issues in street applications and carries a significant price premium. STILLEN's polyurethane eliminates both failure modes. It flexes instead of fracturing, which is exactly what you want from a front splitter or rear diffuser that's going to live close to road level on a vehicle you actually drive.
Finish Options to Match Any Build
STILLEN's polyurethane exterior styling products are available in two finishes: raw, unfinished urethane for easy prep and body-color painting to match your vehicle perfectly, or a factory-quality matte black finish for a clean, ready-to-install look. Whether you're building a stealth street car or want an exact color match, the option is yours.
Fit That's Dialed In Before It Ships
Every STILLEN body styling product is test-fit on the actual target vehicle at our R&D facility before it enters production. That's not a checkbox — it's how we ensure a trouble-free, vehicle-specific installation every time. No trimming marathons. No struggling to close gaps. Just a part that fits the way an OEM-quality product should.
When you choose STILLEN body styling, you're choosing a premium USA-designed, USA-engineered, and USA-manufactured product backed by decades of in-house development.
To order or for more information on STILLEN's full lineup of polyurethane body styling and aero kits: call 866-250-5542 or email us at sales@stillen.com.