Replace your restrictive cats with the Agency Power BMW M3 and M4 high flow downpipes to unleash hidden horsepower from your S55 engine. 

Replacing your stock cats with the catless Agency Power S55 downpipes, will remove all restrictions on your turbos so they can achieve maximum power easier, much faster and keep that power for a wider RPM range. 

On top of the power gains you will also get a very nice exhaust sound upgrade with these high flow Agency Power downpipes.

Catted downpipes will give you 75% of the catless downpipe power gains and sound. It will also remove any fuel smell caused by the absence of the restrictive cats.

Both Agency Power M3 / M4 downpipes are offered in brushed and black ceramic coated finish. 

Catless Downpipes pictures:

Catted downpipes: