What is a decat exhaust

[thexav]

Can you explain what a decat exhaust is, do they give better power and are they legal in the UK?

 

[obi_waynne]

It is an exhaust with the Catalyst removed. It improves flow rate but most cars will fail the UK emissions test if you take out the cat.

It could be a long length of exhaust or just a small pipe which replaces the cat.

Some cars have a smaller pre cat and then a larger cat further down in the exhaust.

A sports cat is a good compromise. I know some drivers who have a pipe they bolt in for off road use to replace the cat and then when they need the car to be legal they just bolt the cat back on.

 

[old-git]

Unless your car's engine is heavily modifed it isn't worth the hassle.