Mustang GT350 – GT500

Table of Contents

• Mustang GT350 Engine Bay Dress Up Kit: What Fits and What Doesn’t
• GT350 vs GT500 Fitment: Model Year and Engine Configuration
• Mustang Door Sill Plate Protection That Looks Show-Ready
• How to Install Mustang Door Sill Covers in Under an Hour
• Shelby GT500 2005-2014 Accessories: What Still Holds Up
• Appearance Upgrades vs. Performance Mods: Where to Spend First
• Conclusion: Build the Bay You Actually Show Off
• Frequently Asked Questions

Last Updated: October 13, 2026

featuring AMT Door Sill Covers:

Mustang Shelby GT350 2015-2020 Door Sill Plate Covers

Our new Ford Mustang GT350 door sill plate covers install over your factory sill plates. Not only do they add show quality looks, drastically enhancing the appearance but they also protect your original sill plates.

Mustang GT350 Engine Bay Dress Up Kit: What Fits and What Doesn’t

Shopping for a Mustang GT350 engine bay dress up kit usually starts with excitement and ends with a return label. The problem isn’t the parts themselves. It’s fitment. A GT350 is not a GT, and it is not a GT500, and a lot of listings treat all three as the same car. This guide from AMT Custom Designs walks through what actually fits a Shelby GT350, what only fits a GT500, and where your money is best spent if you want a show-ready engine bay.

Here’s the honest truth most guides skip: we don’t make a dress up, we just make door sill covers for the Mustangs. What we build for Mustang owners is door sill plate covers, and we’d rather tell you that up front than sell you something that doesn’t fit. So this article covers the fitment landscape broadly, then gets specific about the one Mustang part we make and know inside out.

Engine bay dress up is the practice of adding cosmetic covers, caps, trim, and finishes to the engine compartment without changing how the car performs. The goal is appearance, not horsepower.

Ford Mustang official model history and specifications

GT350 vs GT500 Fitment: Model Year and Engine Configuration

Fitment is the single biggest reason Mustang underhood parts get returned. The GT350 and GT500 share a platform family but not an engine bay layout, and model year changes within each generation shift mounting points and clearances.

The GT350 runs a flat-plane crank 5.2L V8. The GT500 runs a supercharged 5.2L V8 with a completely different top-end profile. A cover shaped for one will not sit correctly on the other. That difference shows up in three places buyers check first: the strut tower brace, the factory engine cover footprint, and the clearance above the throttle body.

Most guides stop at “GT350 and GT500 are different.” Here is the year-by-year picture that actually decides whether a part bolts on or comes back in a box.

Shelby GT500, 2005-2014 (S197 generation)

• 2005-2006: 4.6L supercharged V8, early body and trim-clip layout
• 2007-2014: 5.4L and later 5.8L supercharged V8, revised top-end and strut tower geometry
• Factory strut tower brace and engine cover shapes changed across these years, so a cover that fits a 2007 may not clear a 2014

Shelby GT350, 2015-2020 (S550 generation)

• 2015-2017: 5.2L flat-plane crank V8, first-year body and clip revisions
• 2018-2020: same engine family with updated front-end and underhood trim
• The naturally aspirated top end sits lower than the GT500’s supercharged setup, which changes what clears the hood and what does not

Shelby GT500, 2020+ (S550 generation)

• Supercharged 5.2L V8 with a tall top-end profile
• Strut tower brace and engine cover footprints are unique to this car
• Parts shaped for a GT350 will not sit correctly here, and the reverse is also true

Three things decide whether a part fits:

• Generation and model year, 2005-2014, 2015-2020, and 2020+ bodies differ in both dimensions and trim clips
• Engine configuration, GT350 and GT500 V8s are not interchangeable for dress-up parts
• Existing equipment, factory covers, strut tower braces, and trim panels change what clearance you have

A practical way to check any listing before you buy: confirm the seller names the exact model year range and the engine, not just “Mustang V8.” If a listing only says “fits Mustang,” treat it as unverified. Then measure the clearance above your factory cover and compare it to the part’s stated height. If the seller does not publish a height, ask before ordering.

Side-by-side comparison of a Shelby GT350 and Shelby GT500 engine bay, hoods open, showing the difference in top-end height and strut tower brace layout

Mustang Door Sill Plate Protection That Looks Show-Ready

Mustang door sill plate protection is a thin, finished cover that installs directly over your factory sill plates. It shields the original sill from scuffs and shoe drag while upgrading the look every time the door opens.

This is what we actually make, and it’s our best seller for a reason. Our Ford Mustang GT350 door sill plate covers install over your factory sill plates. They add show-quality looks that drastically enhance the appearance, and they protect your original sill plates at the same time. Nothing gets cut, drilled, or removed.

For GT500 owners, our Ford Mustang Shelby GT500 2005-2014 door sill plate covers do the same job for that generation. Same install-over-the-factory-sill approach, same protection, same show-ready finish.

The logic is simple: your factory sills take the abuse every time someone gets in. Cover them and the original stays intact underneath.

How to Install Mustang Door Sill Covers in Under an Hour

Installation is the part people worry about most, and it’s the easiest part of the whole project. Our covers install over your factory sill plates, so there is no removal step and no modification.

Here’s the process:

1. Wipe the factory sill plate clean and let it dry completely
2. Test-fit the cover before peeling any backing
3. Peel the adhesive backing and align the cover to the factory sill edge
4. Press firmly along the full length, working from the center outward
5. Let the adhesive set before closing the door on it

Most owners finish both sides in well under an hour with no special tools. If you’re coming from a part that needed drilling or trimming, expect this to feel almost too easy.

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Shelby GT500 2005-2014 Accessories: What Still Holds Up

The 2005-2014 Shelby GT500 has a deep aftermarket, but not everything in it has aged well. Parts that rely on adhesive and a clean factory surface still perform. Parts that depend on discontinued clips or trim pieces are a gamble.

Our GT500 2005-2014 door sill plate covers fall in the first group. They install over the factory sill plates, so they don’t depend on any discontinued hardware. You get the same show-quality appearance upgrade and the same protection for the original sills.

A quick way to judge any 2005-2014 accessory:

• Does it install over an existing factory surface, or replace a discontinued part?
• Does it need hardware that’s still in production?
• Is the finish something you can maintain, or does it need re-coating?

If a part fails those questions, keep looking.

Appearance Upgrades vs. Performance Mods: Where to Spend First

This is where most builds go sideways. Owners blend appearance and performance into one budget and then wonder why the car looks unfinished at the show.

They are separate goals. Performance modifications change how the car drives. Appearance upgrades change how it reads to anyone standing next to it. Neither replaces the other, and on a GT350 the line between them is clearer than most owners expect.

Here is the distinction that matters for engine bay parts specifically:

Cosmetic only

• Covers and caps that sit over factory components without touching airflow or electronics
• Trim and finish pieces that add no weight and change no clearances
• Anything that installs over an existing factory surface and can be removed without a trace

Functional or borderline

• Parts that block airflow to the intake or radiator
• Covers that trap heat against the supercharger or exhaust manifolds
• Components that replace factory parts rather than sit on top of them

On a GT350, the naturally aspirated 5.2L runs cooler under the hood than the supercharged GT500, so a cosmetic cover is less likely to cause heat issues. On a GT500, anything that sits over the supercharger deserves a second look before you buy.

Our honest take: if you’re building for car shows, start with the parts people actually see up close. Door sill plates are the first thing anyone notices when they open your door. They’re also the part that takes the most abuse. That combination makes them a smarter first purchase than a cosmetic piece buried under the hood.

A simple sequencing rule that works for most builds:

1. Protect what you already have (sill plates, trim covers)
2. Add what shows when the car is parked and open (door sills, interior accents)
3. Add what shows only under the hood (covers, caps, trim)
4. Add performance last, once the appearance is locked in

Conclusion: Build the Bay You Actually Show Off

The gap between a Mustang that looks finished and one that looks half-done usually comes down to fitment and sequencing, not budget. Get the model year and engine configuration right, install what protects the parts you already have, and build outward from there.

At AMT Custom Designs, we make door sill plate covers for the Mustang GT350 and the 2005-2014 Shelby GT500. We also offer a full line of custom Corvette accessories including engine bay dress-up packages, clear engine covers, frunk covers, door and hood props, tonneau inserts, and interior accents. Every piece is crafted in-house, GM licensed where it applies, and available with custom graphics and finishes.

Get started with AMT Custom Designs and give your car the show-quality details it’s been missing.

Frequently Asked Questions

How can I protect my factory door sill plates on a Mustang GT350?

Door sill plate covers that install directly over your factory plates are the simplest option. They add a protective layer that takes the scuffs from shoes and car show foot traffic instead of your original sills. AMT Custom Designs makes GT350 covers that sit on top of the factory plates, so you keep the original finish intact underneath. If you ever sell the car, the factory sills are still there.

What are the best ways to improve the appearance of a Mustang GT350 at car shows?

Focus on the areas judges and spectators actually see: door sills, interior trim, and underhood finishes. Door sill plate covers with a show-quality finish make an immediate difference because they are visible every time a door opens. Pair that with clean, consistent finishes on the parts you already have rather than chasing a full dress-up kit that may not fit your specific model year.

Do AMT Custom Designs door sill covers fit over factory plates?

Yes. The GT350 and GT500 door sill plate covers are designed to install over your factory sill plates, not replace them. That means no drilling, no removing the original sills, and no risk of damaging the factory finish. The covers add show-quality looks and protect the plates underneath at the same time.

Are custom door sill covers worth it for a performance vehicle?

If you show the car or care about resale, yes. Door sills take constant abuse from entry and exit, and factory plates show wear fast. Covers protect the original finish while adding a custom look. For a performance vehicle you plan to keep or sell later, keeping the factory sills clean is a small detail that adds up.