The life of an exhaust system
Factory stock downpipe
The downpipe on your turbocharged car is part of the exhaust system, which directs the exhaust gases out of the turbine housing and into the exhaust system. Most downpipes comes with a catalytic converter built in. It is fitted between the engine and the muffler.
Without going into too much of the chemistry, a catalytic converter is a honeycomb structure coated in rare metals such as platinum, palladium and rhodium built within a ceramic structure. The honeycomb design helps the emission gases to come in contact with a bigger area at once, so that it works more efficiently.
Inside a catalytic converter
A catalyst in chemistry is basically something that helps a reaction take place. The metals function as a catalyst, reacting with the emissions and converting harmful exhaust emissions to less harmful pollutants. It needs to be very hot to work efficiently which explains the use of ceramic as ceramic gets very hot and stays hot for a long time. Without these three-way catalytic converters, gases like nitrogen oxides, carbon monoxide and unburned hydrocarbons are emitted into the atmosphere, causing large amounts of air pollution.
In short, yes it does. A popular procedure done by enthusiasts is to completely remove the catalytic converter. Removing the catalytic converter(aka de-catting) creates a straighter and less restricted passage for the exhaust fumes to be released quicker and more efficiently, in turn letting your turbo spool faster thus generating more boost and power. The amount of power increase depends on how restrictive the converter was and what other modifications are made.
Here's an overview of the pros and cons of removing the catalytic converter -
Catalytic converters places an engine back-pressure caused by constricting the exiting exhaust gases in order to convert them. With that said, modern cat converters are designed to be much more efficient. In fact, there are even performance cats that have been shown to improve horsepower. De-catting alone does not mean you'll gain a lot of horsepower but it can help to maximize the potential of your tune, if you decide to go for a tune.
Catalytic converters also work like a muffler on most vehicles. Removing it gives your car a more distinctive, deeper and louder sound.
The constrictive nature of a catalytic converter may place a strain on the engine so it has to work harder to churn out the same amount of energy. Removing it helps the engine to perform better.
The catalytic converter was invented for this single reason, to reduce the harmful gases emitted from a vehicle. Removing your cat converters not only contributes to many forms of environmental damage(one example being acid rain, you can look it up, it's pretty nasty), it immediately affects the local air quality around you, causing harm to you and those around you. Going cat-less is illegal for a reason. A single car made in the 1960s would emit as much harmful gasses as a hundred modern cars fitted with catalytic converters today. That is a huge deal. With over 1 billion cars around the world, just imagine how much pollution there would be if the catalytic converter had not been invented.
In Singapore, it is not allowed to remove your catalytic converter if you're not directly replacing it. You likely won't be able to pass an emission/inspection test and on the road, the sound and smell coming from your exhaust is like blood is to sharks for patrolling LTA officers; with you ending up with a hefty fine.
De-catting means all the nasty fumes are exhausted full force and people around your car will definitely notice the pungent and strong exhaust smell emanating from your car. Even in the driver seat, you'll probably notice it with the windows down or at a stoplight. But of course, this also depends on how sensitive you are to such smells.
Your engine check light will most probably come on and stay on. This is more of an annoyance but it could also hinder you to be alerted about other issues your car may actually be having. But this can be solved by putting in spacers for the oxygen sensor or a tune.
Wagner aftermarket downpipe
An aftermarket downpipe can offer a significant improvement in performance without necessarily having to de-cat. You can use an aftermarket downpipe legally if it's approved by the LTA, but that also means you have limited choice. Popular brands like Wagner, Akrapovič, Eisenmann offers quality aftermarket downpipes/exhaust. Some of which are LTA approved according to 9tro's LTA approved exhaust list, click HERE for the list. If you don't care for it to be approved, then you are free to choose whichever that fits your car.
There are aftermarket downpipes that comes without a catalytic converter and those that come with a high flow catalytic converter. High flow catalytic converters has converters that has a lower CPSI(cells per square inch). The main principle is that the lower the CPSI, the bigger the cells are, the lesser the cell walls = lesser restriction. So a 100CPSI catalytic converter has holes 5 times the size of a 500CPSI cat converter.
600CPSI on the left, 200 CPSI on the right
So to make it clear, a higher CPSI number does not mean higher exhaust flow. The more cells per square inch means more cell walls and smaller passageway within a square inch. Which does a bang up job for emission control as more exhaust fumes comes into contact with the cell walls and the cat converter is able to do a more thorough job. In turn, the passageway is much more restricted due to the higher amount of cell walls and smaller air way for the exhausts to flow through.
If you're not planning on tuning your car, most share the consensus that it's just not worth the trouble for a meager amount of gain. Though if you choose to, it does still benefit your car as the turbo will be able to spool quicker because the air flow is less restricted. Without a tune, you can maybe gain around 10-20whp. But if you're planning on tuning your car then it might be quite worthwhile to look into upgrading your downpipe, be it high flow or cat-less at your own risk. The gains will vary depending on what modifications or tune you're planning to do along with modifying your downpipe.
Whether it is worth the risk and the trouble really depends on how far you want to take your car and what do you want out of it. You could want to de-cat simply because you're fond of the sound or you could do it because you take your car to the tracks every now and then. It's best to really find out what you want to gain out of either getting a cat-less or high flow cat downpipe and whether you will be able to get what you want out of it.
Take a look at our catalog by clicking HERE for a range of downpipes and exhausts by clicking here, or if you need any help in choosing the right downpipe, do not hesitate to contact us on Whatsapp using this link https://wa.me/6597883616 or email us at email@example.com
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