Does a cat back exhaust increase horsepower?

Answer 1

That term refers to the portion of the exhaust from the catalytic converter on back to where it ends at the rear of the vehicle.

They generally use larger pipe than the stock system. Good systems will have mandrel-bent turns that allow the exhaust gas pass with as little back pressure as possible. The mufflers in these kits are often glasspacks to reduce back pressure.

It is more of a improvement in sound than performance, it will help achieve a deeper sound that is lacking in small displacement engines and improves horsepower very little.

An improvement is there but hardly worth the cost as a performance upgrade.