hi everyone, i sold my cat when i took my car apart because i was planning to buy a whole new exhaust but my budget changed and im working with the stock system for the time being. i have a straight midpipe in place at the moment but im wondering if i need to find a way to reattach the long tube that used to go to the cat? its an s5, will my 5th/6th ports still work? i’m a bit confused as to what the tube does. thanks!

 

The tube that goes to the cat is for the air pump (driven by a belt on the engine). It provides more air to help the cat burn off any unburnt fuel in the exhaust. It won't have any effect on your 5th/6th ports, but the OEM (or OEM replacement) cat could clog overtime if you run it without the air pump.

 

ok awesome! thanks so much!

 

Unlike the s4, which has a nipple coming off the long tube that feeds the 5th and 6th port actuators.

S5 uses the air control valve to actuate.