How I built the perfect exhaust system for half the price of a catback
A bit of maths and some elbow grease is all it takes
After 5 months of mucking around and fine-tuning, I've finally finished the exhaust system on my Passat CC. With the famous VW VR6 under the bonnet, releasing the iconic sound I've loved for years was my first priority when getting the car. But after receiving quotes and advice from various exhaust shops, I was left underwhelmed, as none of them could be confident the new system would be free of drone. And with the CC being a big, comfortable cruiser, I really didn't want to ruin the car's calming personality with endless eardrum destruction.
So I did some research and stumbled upon the J-Pipe resonator. A brilliant example of simple physics at work, and used by AMG in their own factory exhaust systems, the J-Pipe (also called Helmholtz resonator) is a sealed, dead-end pipe that works by offsetting soundwaves against each other to create a noise-cancellation effect. The pipe is calculated at one-quarter the length of the drone's soundwave, so that when it travels to the end of the pipe and back, it's de-synchronised by exactly half a wavelength. This causes them to negate each other and virtually eliminate drone. The length of the pipe is determined by your engine type, and what RPM you want the cancellation to take place at.
I've filmed the whole process from start to finish, as there was a lot to consider in the process, and I wanted to create my own video as a guide for anyone looking to give their car the same treatment!