The flex piece - necessary or superfluous for tuning?

The sense behind the flex piece: A flex piece, also called a flex pipe, is the connecting piece between the exhaust manifold and the rest Exhaust. This connector is particularly important as the engine moves when you accelerate, shift gears and take off the gas. These movements are not large, but unwanted forces would act on the entire exhaust system if the connector were not flexible.

The difference in tuning

The flex piece is only a connection piece and does not differ in function in any expansion stage, as it is about creating a flexible connection between the engine and the exhaust system. However, it is recommended that the flex piece is also adjusted if certain changes are made. These changes can be a change in the downpipe and the exhaust system. If the diameter of both components is changed, it makes sense to adjust the flex piece accordingly in order not to create a bottleneck for the exhaust gases, which would result in increased exhaust back pressure, which in some cases can even reduce the performance of the vehicle. The factory-made flex piece can be replaced by an improved stainless steel variant and an existing difference can also be compensated for by means of stepped flex pipe connectors. Modified flexible pipes are usually more stable and have a longer service life than the components ex works and can be supplied in a wide variety of diameters suitable for every exhaust system.

Legal information about the flex piece!

Changing the flex piece has no positive effect on the sound or performance of the vehicle, which is why it can be changed at will, provided that the function is still guaranteed.

What to pay attention to?

The most important thing when changing the flex piece is that it continues to perform its full function and minimizes vibrations in the exhaust system. So that there is no taper in the exhaust system that has a negative effect on the performance and power delivery of the engine, the flex piece should be matched to the inner diameter of the down pipe and the exhaust system. Another point to keep in mind is that the flex piece can tear too. As a rule, this only happens after a few years and is completely normal since forces are constantly acting on the flexible pipe, but the repair is relatively cheap.

Which vehicles are particularly suitable for this and why do you do it?

Most vehicles that have a modified flex piece are turbocharged. Popular models are the Golf R, the Cupra R and other sporty vehicles that require a larger exhaust system to optimize performance, as more exhaust gases are produced. The flex piece must also be adapted so that the flow is not disturbed or reduced.

Is it useful or unnecessary?

If you only change the exhaust system to achieve a better sound, you do not need to change the flex piece. However, if performance optimization is imminent, it is advisable to adapt the flex piece if the downpipe and the exhaust system have to be replaced.

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  1. says: Mark Williams

    Thank you so much for this post. I love the part where you talk about ”The flex piece - necessary or superfluous for tuning? ".

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