Catalytic converters are so good at protecting the environment as they convert the harmful pollutants of exhaust into less harmful ones. But, when you hollow out your catalytic converter, it offers lots of benefits!
So, how to hollow out a catalytic converter? Well, you can hollow out your catalytic converter following simple steps. First, take your cats off from the car. Now crumble the core and reinstall the cats in the previous posts!
Quick FYI, this is not as straightforward as it may seem. You need tools and exact steps to help you carry out the process.
That’s why in this post, I will break down simple steps to hollow out a catalytic converter step by step and discern everything unknown around it. So stick around.

Here’s the Process of Hollowing Out a Catalytic Converter
Pondering over how difficult the process would be. Well, no more worry because I will be showing you everything you need to know about hollowing out catalytic converter steps by step.
Method 1: Hollowing A Catalytic Converter By Removing It
Necessary Tools
- Wrench.
- Vice
- Crowbar
- Hammer
- Two-floor jacks
Step-By-Step Guide
1. Taking the cats off
The first step of hollowing out cats is to get it out. This requires a vice to hold it together and use the crowbar and hammer to get it out.
But, before that make sure you wear protective clothing to avoid inhaling the catalytic substance otherwise it will cause harmful effects on your health.
Start out the process by fixing the converter’s position to eradicate the core. To do it simply reverse the cats’ position.
2. Reinstall the cats
Once you removed the core, you can simply place the converter into the exhaust and screw the bolt back in place. Ensure that the screw is tightened and capable of preventing it from falling off. You can check it with a test run.
Method 2: Hollowing A Catalytic Converter Without Removing It
Necessary tools
- Hammer
- Air compressor
- Steel knife
- Pneumatic lift
- Safety equipment like fireproof goggles and hand gloves
- Steel knife
- Chisel
- Cold weld epoxy
- Plier
Step-By-Step Guide
Step-01
The first process in this method involves lifting the vehicles. You can do it by using a jack. This tool helps lift the car and cool off before you start the process.
Step-02
Now, it’s time to figure out where your catalytic converter is attached. Usually, it is attached underneath your vehicle.
Step-03
Now, it’s time to bend the cut flap. You can do it by using a crowbar. It will allow you to bend down the cut flap. Keep cautious while maintaining this as you might cut it off entirely!
Step-04
At this stage, you need to connect the seal kit and flap. To do this you will need a welder. Put on your welding goggles and use the arc welder to melt the steel wire. Putty steel knife will help here to reshare the metal despite being hot.
Step-05
Now gently hammer down on the honeycomb structure and break it. But, keep your eyes sharp and let not damage while carrying out the process.
Step-06
Use pliers to bend down the flap back to the cover as you are done removing the converter. This will take sufficient strength so this may overwhelm you but don’t allow it to hurt you.
Step-07
There you have it, man. All you need to do is weld the flap. Welding the flap will enable you to avoid leakage.
Interested in this method? Deep dive: how to hollow out a catalytic converter without removing it
Method 3: Using Test Pipes
You can even achieve the same results following this method using a test pipe. In this section, I’ll show you how to use test pipes to hollow out the cats step by step. So keep reading.
Necessary Tools
These tools will help you to carry out the same process of hollowing out the catalytic converters using test pipes.
- Wrench (To screw the bolts)
- Two-floor jacks (To uplift the car)
Step-By-Step Process
Step-01
The first step is to get off the catalytic converter as always. So first, locate the converter. Usually, the cats are attached to the vehicle. Once you locate this, you need to uplift the car from the ground.
A car lifter too like carjack will help you here. Use that and crawl under the car. Go take off the cats using a wrench by loosening the bolts and detaching the converter from the exhaust.
Step-02
Now install the test pipe as you successfully removed the core. Once you install the test pipes, you can use it when you wish to get the benefit of hollowed cat.
Is it legal to install a catalytic converter?
There are some states where it is not legal to hollow out catalytic converters. It is because their environmental issues associated with this.
To remove it, you must follow the environmental guideline 1986 initiated and ruled by the environmental protection agency.
So, if you remove it anyway and get spotted, you will get punished as a violation of the law. This punishment might include not allowing you to drive for some period.
Also Read: Will high-flow cats pass the emissions?
Is it bad to hollow out a catalytic converter?
Hollowing out catalytic convert is actually bad for environemnts although it can provide some amazing benefits. But, in some (most of the) states its not allowed to run a test pipe let alone hollow out cats. Its a clear violation of the law there. So, yea from the environmental and legal parspective hollowing out cats is definitely a bad thing.
Pros And Cons Of Hollowing Out A Catalytic Converter
Like everything under the sun has pros and cons, this process is no an exception to that rule. Check below what are the pros and cons of hollowing out a catalytic converter.
Pros
So, what are the benefits of hollowing out a catalytic converter? Well, it actually got some amazing benefits that might inspire you to take the decision of hollowing out firmly!
1. More horsepower
Hollowing out increases the horsepower of your car’s engine. It works because gutted cats create back pressure on the engine.
When you hollow out a catalytic converter it helps compress the exhaust before they are expelled with added speed from the car’s system. This also improves the efficiency of the engine.
Keep in mind that the boost in horsepower by hollowing out the catalytic converter may vary depending on your car’s model.
2. Better exhaust sound
Everyone likes that smooth buttery, loud and powerful exhaust sound, right? What if I tell you that you can change the existing exhaust sound to a whole new level. So, what does it take to get you there?
Well, you can get there by hollowing out your cats! It will free up the path that holds the sound of exhaust.
Hollowing out exhaust also changes the effect of the gases released during fuel combustion.
3. Lower temperature
It always should be your target to keep your engine’s temperature in check as a car owner. This will eliminate friction and the tendency of wear and tear.
Why?
It takes the engine extra work to generate power when you install exhaust tips which heat up the engine. But, hollowing your cats helps free this up and reduce that extra heat.
4. Increased gas mileage
Hollowing out your cats can even increase gas mileage. How? Well, since the engine requires more work when a catalytic converter is installed it will use more fuel, right?
As hollowing out cats frees that up, it can increase the gas mileage.
Cons
After coming here reading all the pros you might be a little disappointed because there are some concerning cons.
1. Environmentally detrimental
The first problem associated with cats is it’s environmentally unsafe and that’s why many US states ban them.
Hollowing out catalytic converter means exhaust will have no ways to convert harmful pollutants into less harmful ones as the cats will be hollowed out. This will create a bad effect on the environment.
2. Loud exhaust
Hollowing out cats can increase the noise which many people won’t like. The safe level of noise for humans is 85 decibels but when you hollow out your cats, it can produce noise even more than that level.
Parting words
So, we have come almost to the end of the post. Hollowing out your catalytic converters can boost the performance of your engine and other amazing stuff. But it also has pitfalls associated with it.
So, deciding whether you hollow out the cats is all yourself. There are multiple ways to hollow out and I’ve shown all those so that you can easily keep pace with the instruction and do it yourself.
While carrying out the process especially when you take off the existing catalytic converter make sure you wear protective clothing so that you can keep yourself safe from harmful particles of the cats.