Boost Horsepower with High-Flow Catalytic Converters

Howdy folks, Ed here. Welcome back to Bullnose Garage. Do you ever feel like there’s a silent thief lurking in the bowels of your ride, stealing your performance, wrapping your precious horsepower up in endless red tape, and literally choking off the airflow that makes your engine come to life? Yeah, I’m talking about emissions, specifically catalytic converters. Power robbing, crime inspiring, and pocketbook draining cats are a double-edged sword of eco-responsibility and pain. But here’s the thing: you can do something to take back some of that power. Today, we’re talking about cat options, from keeping your ride stock all the way to cutting the cats out completely. Specifically, we’ll talk about high flow cats, how they work, what they can do for you, and I’ll check out the ones that just landed on my workbench, courtesy of Dinox. But don’t get too excited just yet. High flow cats can definitely give you back some of the horsepower that the EPA stole from your ride, but you might think twice when Johnny Law comes knocking. Dramatic? Maybe, but it’s definitely something you need to know. Stick around.

Hello! Now, before we dig into the nitty-gritty, I need to give a shout out to Dinox for sending me these high flow cats. They’re a great example of the kind of equipment I’ll be talking about. And if you want to grab a set for yourself, Dinox’s Black Friday sale kicks off on November 27th and runs through December 2nd, offering up to 50% off. So if you’re looking to nab some exhaust or intake parts, this is the time to strike. I’ll circle back with some more details.

Okay, so let’s kick things off with the basics. A catalytic converter is a component of your exhaust system responsible for cleaning up the exhaust gases before they exit the tailpipe. Inside, you’ll find metals like platinum, palladium, and rhodium, the MVPs of emissions control. These metals work like catalysts, starting up chemical reactions without burning out in the process. They’re also why some sketchy characters love to hack your cat off with a saw. Those metals are worth a boatload, even in the small quantities you find in a catalytic converter. Catalytic converters pull off a nifty bit of chemistry to break down pollutants. There are two stages to the job that they do. In the reduction stage, platinum and rhodium split nitrogen oxides into harmless nitrogen and oxygen, cutting down smog forming emissions. Next up is the oxidation stage, where platinum and palladium make carbon monoxide, a toxic gas, react with oxygen to become carbon dioxide. Any unburned hydrocarbons are also oxidized, turning into CO2 and water vapor. Think of it like a little high temp lab under your car, turning nasty exhaust into something a bit more eco-friendly.

OEM cats are all about compliance, standardization, and appealing to the mass market. That means hitting strict emissions targets, cutting costs, and keeping things quiet. Horsepower? Not a top priority. Because of that, they tend to choke your exhaust flow in order to meet their main objectives. High flow cats, though, are built for performance. They’re designed to let more exhaust pass through with less resistance. It’s kind of like trying to sip a thick milkshake through a tiny straw versus taking a big gulp through a wide straw. The benefit is less back pressure, and that means better exhaust scavenging, which translates into improved horsepower and torque. Now, for those running performance mods like aftermarket headers, camshafts, or stroker builds like my upcoming 408 stroker Windsor here, high flow cats can make a measurable difference.

High flow cats use more open cell substrates with strategically placed channels to keep exhaust flowing efficiently while still catalyzing those gases. Most high quality models, like this 3-inch unit from Dinox here, feature stainless steel construction for durability against heat and corrosion. The cells per square inch, or CPSI rating, in high flow cats is lower than in OEM units. Lower CPSI means fewer tiny channels for gases to navigate, reducing restriction. But don’t worry, these cats still do their job at cleaning emissions, though they may not be certified to do it. That certification can be a bit of a problem when it comes to federal or state compliance with emission laws. Here’s where things can get a bit controversial, especially with gear heads and shade tree mechanics. Most high flow cats, like these, are not federally compliant.

Okay, so let’s get into why compliance matters. CARB, or the California Resources Board, sets the gold standard for emissions regulations, which a few states use as a benchmark. If it isn’t CARB compliant, it doesn’t meet their rigorous standards. These non-compliant cats, like the Dinox cats I’ve got here, can’t legally be sold or used in states with CARB regulations. That’s California, New York, Maine, and Colorado. Why? Well, CARB compliant units have additional testing and require certification to meet stricter emission targets. So if you’re in or plan to sell your vehicle in one of those states, you got to keep that on your radar. It could mean the difference between passing emissions or failing. My state, New Mexico, doesn’t currently follow CARB, so I was able to get my hands on these. Also, keep in mind that modifying your exhaust or emission system, including adding high flow cats that aren’t EPA certified, constitutes tampering as far as the EPA and federal government are concerned. Tampering is a specific term, and that means installing these on your vehicle to replace your stock cats can be a bit problematic in terms of legality on a federal level, even if they’ll work as well as a certified unit and they’re legal in your state. I won’t tell if you won’t.

All right, so let’s take a look at these Dinox units themselves. Right out of the box, they look like they’re pretty high quality, made out of stainless steel, which is great when you’re dealing with temperatures up to 1200°F in your exhaust. So you definitely want something that’s nice and robust there. And you know, I haven’t put these on, obviously. I haven’t tested them yet, but they look good. I did a review of some Dinox headers a couple months ago, and they looked really good too. So, you know, the quality seems to be there. As I’m looking through, you can see where the high flow channels all are in there. You can see right through it. Looks really good. I don’t see any debris. I don’t see any broken bits. I don’t see anything in here that would indicate to me that it’s not high quality. So I am really looking forward to getting these on the vehicle and seeing how they sound and seeing how they work. So, yeah, I’m pretty impressed with these units I got from Dinox. So, shout out to those guys. We’ll see if they live up to the hype.

Installing a high flow cat is pretty straightforward if you’re handy with an angle grinder and a welder. Remember, positioning is key. You want it close enough to the engine to heat up quickly, but far enough down the line to avoid excessive back pressure. Always test fit your new cat, check clearances around your undercarriage, and, you know, make sure that it’s going to fit. A misstep here can lead to rattles, leaks, or even worse. High flow catalytic converters really come into their own when they’re used in a modified vehicle with higher than stock airflow requirements. If you’re rocking a turbo setup or even a naturally aspirated engine with some serious upgrades, that’s where high flow cats start paying dividends. If your car or truck is just a weekend grocery getter that’s more or less stock, high flow is going to be overkill. There’s a lot of other more effective, less controversial mods you should probably do first. But for anyone with a build designed to breathe freely and rev high, that’s a performance edge worth considering, especially if you’re rebuilding it anyway.

So let’s take a moment and talk about the possibility of running an exhaust setup without catalytic converters at all. It’s an option some performance enthusiasts choose because it completely eliminates exhaust restriction, which can result in even more horsepower. But here’s the trade-off: no cats mean more pollutants and potential much louder exhaust notes. And while it might be tempting to ditch the cats entirely for the sake of raw performance and more noise, it comes with its own set of challenges. Not only are catless builds illegal for street use in most places, but they can also trigger check engine lights and issues with your vehicle’s ECU. Even if it’s strictly on an older vehicle without those issues, it’s not a great environmental choice. That’s something you have to decide for yourself. That’s where high flow cats come in as a smarter middle ground. They allow you to maintain a respectable level of emission control, stay compliant in less restrictive areas, and still reap the benefits of better flow and power gains. Plus, they help avoid some of the complications that come with going fully catless, like failed inspections, binds, or ECU and check engine lights. So if you’re looking for a balance between power and practicality, high flow cats might just be the way to go. That’s why I’m choosing these for my build for those very reasons.

One other thing to keep in mind is that high flow cats can sometimes lose efficiency faster than their stock counterparts due to their more open design. Now, while you can’t exactly service a catalytic converter like other parts, there are a few preventive measures you can take to keep them functioning well. Regularly checking your exhaust leaks, ensuring the fuel mixture isn’t running too rich, which can clog the cat with unburned fuel, and keeping the engine in good tune will help prolong the life of your catalytic converter. High flow cats can be extra sensitive to contaminants, so using high quality fuel and avoiding oil burning is also a good thing to remember.

So before we wrap things up, just a reminder: Dinox’s Black Friday event starts November 27th and runs through December 2nd, up to 50% off. It is definitely worth checking out, especially if you’re considering an upgrade. Go check them out at dinoxparts.com, that’s dinoxparts.com. All the information will be down in the description below. A shout out to Dinox for sending me these cats. They’re not paying me for this review; they just sent these to me and asked me to put something up about them, and I thought that’d be a great opportunity to explain how high flow cats work and go through the whole thing. So thanks again, Dinox, for reaching out and supporting a small channel like myself. I really appreciate that.

So are high flow cats in your future, or are you more of an OEM purist? Or are you just going to ditch all that emissions garbage altogether and tell the EPA to go pound sand? Drop me a comment and let me know what you think. If you found this video helpful or interesting, or if you learned something, give me a like and a subscribe. That really helps me out. And like I said before, drop me a comment and let me know what you’re thinking. Also, if you have any questions, comments, concerns, gripes, internet ramblings, stick them below. You think I’m a shill for Dinox? Let me know. I’m never going to turn down free stuff. And if you think that I’m going to get in trouble with the EPA by installing high flow cats on my truck, let me know that too. Thanks again for watching, guys. We will see you next time, tinkering away, getting things to shine. Garage is considered divine. Thanks again for watching. We will see you next time.