If you’re ready to purchase a catalytic converter shield for your vehicle but you’re not sure where to start, ask yourself these questions:

1. What is the shield’s fitment and compatibility with my vehicle?

When choosing the right catalytic converter shield for your catalytic converter, it’s important to verify the make, model, and year of your vehicle, as well as review any modifications you’ve made to your car to determine if the shield is compatible. For instance, if your vehicle has an aftermarket converter, lift kits, or a modified suspension, certain shields may not fit perfectly.

Be sure to check the shield’s list of compatible vehicles and ask questions if you’re unsure. With aftermarket parts, you may have to determine whether or not you will need to cut the shield or move parts around to make the shield fit your catalytic converter.

2. Where is the shield made?

Be cautious of shields made overseas, as they may be made with cheaper materials and use questionable hardware. During and after install, you may have questions about installation and fitment, and you want to make sure the shield manufacturer has a reliable support center to answer any questions that may come up.

Here at Miller CAT, we design and manufacture our products in the USA (Santa Clara, California) and use only the highest quality materials from domestic suppliers - 12 gauge premium grade 5052 aluminum and 304 stainless steel. We can answer any questions prior to purchase to help ensure you are buying the right shield for your car. If you or your installer have any questions during or after installation, we’re here to help in any way we can.

3. What type of security features does the shield and its hardware utilize?

With the growing number of copycats and cheap alternatives, many shields use common torx screws that can be easily removed with torx bit keys. Not only is material quality important, but also the hardware that the shield uses. 

Miller CAT has two levels of screws. Our Better Level uses patented tamper-proof screws, which means no one can buy these screws or keys online at their local hardware store. For those who want to go the extra mile, we also have a Best Level (available for some models), which is a proprietary custom screw and key, complete with “MILLERCAT” etching on each screw. See the difference and ultimate level of protection we consider when designing our shields.

4. Does the shield consider proper heat extraction?

Proper heat extraction for your vehicle is vital, as catalytic converters operate at 400-1000+ degrees. A good shield should address stagnant air and reduce excessive heat. There are some designs that simply cut slits or holes into shields and do not efficiently extract heat. Read more to understand the temperature testing that we do at Miller CAT.

5. Will my vehicle pass a smog test with the shield on?

According to the California Bureau of Automotive Repair, “A vehicle will fail Smog Check if the theft prevention device modifies or damages the catalytic converter or if any required identifying information is not visible. In addition, a theft prevention device should not be welded or attached directly to the catalytic converter.”

When purchasing a theft prevention device, make sure that your shield will not modify or be attached to the catalytic converter. The CA BAR provides a great search tool to find a licensed auto shop. Read our recent blog about the impact of certain theft prevention devices on your Smog Check.

6. Do I have the tools necessary to install the shield or a trusted mechanic to handle my install?

We recommend professional installation with a trusted auto repair shop, not only for your safety, but also because the shops are typically equipped with certain tools that you may not have at home.

For instance, there are a few Miller CAT shields that require a rivet nut tool during installation. While we aim to make our shields as easy as possible to install on your own, if you are not confident in your abilities, it may be best to leave it to the professionals.

7. Can the shield be removed for routine maintenance yet remain secure from thieves?

Consider the routine maintenance that your vehicle will need, such as oil changes. For larger maintenance jobs such as transmission oil changes, O2 sensor replacement, or exhaust repair, you may still need to remove your shield. Because of this, it’s absolutely critical that your shield can only be removed at your discretion, with your security keys. It’s also important to note that your shield should never be permanently affixed to your vehicle!

Here at Miller CAT, we understand the importance of security and we’ve worked tirelessly to design the best catalytic converter shields on the market. We hope this can be a good start as a catalytic converter protection selection guide, but we’re also here to answer any questions you may have. Feel free to reach out to support@millercat.com prior to purchase!