2 ¼”… 2 ¾“… 3” exhausts... Does size matter?

20 years ago, exhaust systems rated low on the manufacturer’s design budget. But nowadays, an exhaust system is an important part of the noise, power and emission system. On most modern EFI Diesels, unless an exhaust is upgraded in conjunction with a chip system, the upgrade gains on power and torque are generally useless. Remember, the chip is the one that does the tuning so it’s always the first choice. The magic of modern day exhaust upgrades on modern EFI controlled diesels (like common rail ones) hinges on the ability of a performance chip to increase fuel flow, and not so much on the exhaust's ability to help gas flow.

There is always a perfect size for pipes and probably, the most perfect would be one that starts at 2” and gets larger towards the tail pipe at 3”. These types of exhaust used to be called ‘Tuned Pipes’. Due to time and cost restraints, exhausts are generally one size fits all nowadays. The most common in the 4WD arena is the 3”. This may be a little big for diesels under 3 litres but it gets the job done and I haven’t been able to record any difference on the same vehicle between varying pipe sizes.

The exhaust industry has yet to come up with technical reports to back up what it’s currently doing. So, we will accept that bigger MAY be better... for now. In the meantime, we can rely on the fact that most manufacturers never imagined their vehicles towing 3,000kg for 3 months straight at close to full load whilst possibly well overloaded. If you fit into this category (you would be surprised how many of our rigs do), then modifications like exhaust upgrades - coupled with proper tuning on older diesels or a chip upgrade on new diesels - are on the table.

Safe Driving!

Andrew Leimroth
Berrima Diesel