There are different ways of hollowing out catalytic converter. But most of them require taking off the exhaust first. But, is there any way other than this?
Yes, you can hollow out your cats without removing them. Amazing, but how to do it? Hollowing out a catalytic converter without removing it will require you handful of tools. Tools like a car jack, wrench and hammer will help you access the cats and break the core.
Hollowing out cats opens up loads of opportunities like increased horsepower, gas mileage, and better sound. It’s illegal to hollow out cats as it can cause harmful effects on the environment. So, hollowing out the catalytic converter without getting off from its position may help you outwit law enforcement forces to detect.
Seems interesting? Read on!

Required Tools
No more fluff! Here are the tools you need to follow through the process I will be showing you in minutes.
- Chisel
- Crowbar
- Carjack
- Air compressor
- Putty steel knife
- Grinding wheel/ Welding torch
- Broad-nosed pliers
- Ball pen Hammer
- Steel wired Arc welder
Put these tools together as you are about to follow through with the exact process required to hollow out your catalytic converter.
Step-By-Step Guide to Hollowing Out Cats Without Removing It
So, you are going to hollow out your catalytic converter without taking it off. There’s a way to achieve it and that is breaking the core without damaging the cats. To do so, technically you will need to remove it although you will reinstall it afterwards. The process is known as “Gutting”.
Let’s start with how to hollow out your converter without removing it from toe to toe.
1. Uplift your car
The first step is to lift your car from the ground so that you can easily access the back of the vehicle.
2. Locate the converter
The next step is to figure out where the catalytic converters lie underneath your car chassis.
3. Bend the cut flap
Once you locate the cats, you can cut the flap. While cutting the flap be wary that you don’t cut it off completely.
Now, make use of a wheel grinder (alternately welding torch) to form a proper flap at the base of the converter.
If you are facing trouble in opening catalytic converters, check out how to remove catalytic converter bolts.
4. Attach flap and seal kit
Before you start, wear welding goggles as at this stage you need to weld in order to attach the flap and seal kit.
Now use the arc welder and melt the steel wire. You can then use the putty steel knife and give shape to the melted metal even if it’s hot.
5. The main part: break down the converter coving
At this step, you need to break the cover of the converter. A flat hammer is all that you need to break it. When you get there you will see a honeycomb-like structure, it’s that you will break. When you attempt breaking it make sure you hammer down it gently so that it doesn’t damage entirely.
6. Close the flap
Make use of pliers to bend the flap and get it back to cover the opening. You might get overwhelmed doing this all alone as it takes massive strength. However, it’s totally possible. Just make sure it doesn’t hurt you while carrying out the process.
7. Finally
So, you are almost done only but welding the flap. Seal the flap to prevent leaks.
So, those were the exact steps to gutting your catalytic converter without removing it.
Benefits of Hollowing Out the Catalytic Converter
There are tremendous benefits of hollowing out catalytic converters. Skipping the downside of it, you will be amazed by all its benefits like:
1. Improve gas mileage
You will notice a significant improvement in gas mileage as you hollow out the catalytic converter.
When cats are attached to exhaust it requires the engine to do extra work which consumes more fuel. Hollowing out the cats will decrease such extra work and improves the efficiency of the engine.
That said hollowing out a catalytic converter can be very economical.
2. Increase horsepower and engine efficiency
A gutted Cats creates a substantial amount of backpressure on the engine, which enables the engine to produce a boost in its power. Although it varies from model to model. However, you will see some sort of efficiency boost once you take off the cats.
3. Keep engine cool
Since the catalytic converter requires the engine extra work, it gets the engine hot. You won’t have to worry about the engine getting so hot when you remove the cats.
4. DIY
You can easily hollow out a catalytic converter in your vehicle, unlike many other procedures.
Taking advantage of this is an advantage because you don’t have to spend money on a visit to a technician in order to fix it.
5. Sound
The effect of the catalytic converter changes with the number of gases released by an engine during fuel combustion.
When you get off the cats the sound will be more loud, smooth and more powerful.
How Do You Unclog a Catalytic Converter Without Removing It?
So, you want to clean your cats without removing them? Well, surely you can if you follow the ways laid down.
In short, you can clean your catalytic converter without taking it off from the exhaust by using targeted cats cleaners, fuel additives, and preventive maintenance additives.
Note that, this strategy won’t work if your cats get too clogged. In that case, getting off the cats from exhaust and cleaning would be the best solution. And, I will not also recommend using maintenance additives as such may, even more, clog the cats.
What Happens If You Hollow Out a Catalytic Converter?
When you hollow out your cats you will experience an additional boost in the engine performance, gas mileage, sound and even horsepower.
How?
The catalytic converter is a component attached to the exhaust system of your car’s engine that converts toxic pollutants into less harmful ones coming out from the combustion chamber of the engine through the exhaust system.
This is an environmentally friendly solution. However, installing cats into exhausts takes extra work for engine which otherwise could be used to give more horsepower to the car
So, as you will hollow out the cats, you will immediately experience at least some sort of power boost in the engine. And, as Cats are taken off, it produces better sound.
But, probably the greater benefit is it requires eliminating the extra work required for the engine which saves a lot of energy and turns out a substantial amount of fuel savings. So, hollowing out cats is actually economical as it increases the gas mileage.
In the End
Although it’s illegal to hollow out the catalytic converter you can adopt it for enjoying a nice boost in engine efficiency, performance, sound and even gas mileage.
Since the environmental act doesn’t permit you to hollow out the catalytic converter, I won’t recommend it doing so. Probably people do this because they heard it will increase the gas mileage and cut their fuel costs.
Anyway, throughout the post, I tried to explain how you can hollow out your catalytic converter without removing it.
If you are still in doubt about that ask me in the comment box.