The first step to upgrading the exhaust system on a Challenger is understanding the baseline. For the most part factory third gen Challenger exhaust systems are dual exhaust systems. However, on 2008-2010 V6 models a single exhaust can be present. The layout of the dual exhaust systems remained relatively the same throughout the years.
They are true dual exhaust systems, meaning from the headers to the tailpipe there are two pipes running all the way back. All models will feature an x-pipe in the system as well. Another thing to keep in mind is 2008-2010 models with dual exhausts there is a massive “suitcase” catalytic converter present.
For optimum flow from engines with two banks, a dual exhaust is best. That means factory Challenger dual exhausts already provide a good amount of flow. However, you still may want to increase pipe diameter, swap out the factory mufflers and cats for higher flow options, and/or move up to stainless steel piping.
The size of the pipe diameter plays a huge role in exhaust flow. It’s important to remember there is such a thing as too big of an exhaust system though as engines need back pressure to operate properly.
Unless you plan on heavily modifying the Hemi to make a lot more power, you want to stay close to the factory exhaust size to ensure the engine can keep running strong. Reference the chart below to see what you’re Challenger’s OE exhaust diameter is. Having this as a baseline will help you pick out the right system for your Mopar.