Exhaust Terms 101: Parts of an Exhaust System

If you’re new to purchasing or working on vehicle exhaust systems, then you’re probably unfamiliar with the terms that describe each component. We’ve put together definitions on 10 common exhaust terms to help beginners familiarize themselves. By knowing the basic exhaust terms, you’ll be on your way to finding the right aftermarket exhaust system for your application.

What’s the difference between an axle back vs. a cat back exhaust? Why do some cars have intermediate pipes and others have downpipes? Are a muffler and a resonator the same thing? Our car exhaust terminology guide will help answer these questions and many others.

Exhaust System Parts Glossary

Exhaust System – All the exhaust tubing (and components, like cats and mufflers) that runs from the engine manifold “hot side” down through the exit out the vehicle’s rear or side. This includes the intermediate pipe or downpipe plus the mid-pipe and the axle-back.

Axle Back Exhaust – This section of an exhaust system includes everything from the rear bumper to the rear axle. It starts with the exhaust tips, then uses steel tubing to travel around the rear axle, before attaching to the mid-pipe.

Cat-Back Exhaust – An aftermarket exhaust that replaces everything from the behind the catalyst to the rear bumper. It contains all the axle back components plus the mid-pipes.

Exhaust Intermediate Pipe – The pipe that comes directly off the engine manifold and links the exhaust headers to the cat back system, such as our MRT Sport Touring Intermediate Pipe. These are typically only used in non-turbo engines – if your engine is turbocharged, you should use a downpipe.

Downpipe Exhaust – Strictly found in turbo engines, this is the exhaust tubing that exits on the turbocharger’s hot side and connects to the mid-pipe. It’s used instead of the intermediate pipe found on non-turbo engines.

Mid-Pipe Exhaust – The exhaust tube section that goes after the catalyst. A mid-pipe such as our Camaro SS MRT H-pipe travels under the passenger side and ends before the rear axle. Another way to describe it is the exhaust tube post-catalyst and pre-axle back.

Turbo-Back Exhaust – An exhaust setup for turbocharged engines that contains everything from behind the vehicle to the rear bumper: the downpipe, mid-pipes and axle back. Our 2015-22 Mustang Extreme Off-Road Turbo back exhaust is a great example.

Muffler – A part that changes the exhaust sound level. Factory-stock vehicles typically have a more restrictive muffler to reduce noise levels while performance mufflers are designed to increase the volume.

Resonator – An echo chamber that cancels out certain noise frequencies. This fine-tunes the sound by eliminating harsh unwanted resonance. The resonator typically is found right before the muffler.

Exhaust Tip – The piece that goes on the end of the axle-back exhaust tubing below the bumper or rocker panel. Note the size of the exhaust tip doesn’t noticeably alter the sound – it’s primarily for visual appeal.

Once you’ve gotten the hang of vehicle exhaust terminology, find your exhaust systems and accessories from MRT. Our exhaust parts are handcrafted in the U.S. with a unique design to Hear the Difference, Feel the Performance and Get Noticed.