Is the Decat a worthy option?

The straight answer to this dilemma in most cases is negative. There are many car owners who decide that their catalytic converter produces a severe blockage inside the exhaust system which needs to be eliminated and therefore they completely delete the cat from the exhaust system, and then replace it with a straight pipe. Although such a move will increase the volume of the powertrain and potentially add a few more HP to the engine, in most countries, it is illegal to drive a car without a catalytic converter.

Another way of decatting is to strip the cat. This process means to remove the honeycomb innards of the cat and thus to reduce the amount of restriction on the exhaust gases.

On the picture below you can see a catalytic converter which was completely replaced with a straight ‘decat pipe’.

http://www.youtube.com/watch?v=eA16zSVXnYc

Most car owners who decide to make such a modification on their vehicle decide to take the risk and simply keep their cat waiting to be installed back again in case MOT time comes around. However, if you are caught by a capable police officer the game could be over for you. Also if you consider the potential increase in power depending on the engine size, a sports cat might be a much more potent solution if you really think that the factory cat on your vehicle is holding its powertrain back.

And here you can see the outcome of a ‘DIY’ cat stripping.

Bear in mind that the result of deleting the cat will be amplified in a vehicle with turbocharged engine, because when you remove the precatalytic converter an increased flow of exhaust gasses into the turbo is allowed. The catalytic converters function best at high temperatures, so a precat is a smaller model placed higher up the exhaust system that helps break down the emissions at start-up when the engine runs full of exhaust gasses.

In a turbo exhaust system, the precat is generally placed just upstream of the turbocharger, which is why its removal would derestrict this area of the exhaust. Still, that would be considered as tampering with the standard emission controls of the exhaust system which is why it is illegal in most countries.

Below you can see the exhaust system of the Subaru WRX that shows the precat just upstream from the placement of the turbocharger.

After reading this article we would like to hear whether you’ve considered switching to a sports cat or take your chances with a complete decat pipe? Share your thoughts with us on such a common, but risky car modification in the comment section below.