Originally Posted by spec 123
dOING IT FOR A SHORT PERIOD OF TIME MIGHT BE OKAY BUT LONGER THAN A WEEK OR FREEWAY DRIVING WILL CAUSE DAMAGE TO YOUR CATALYTIC CONVERTORS. BMW ADDED THIS DUE TO THE NOISE REDUCTION BUT ALSO THE DUAL PIPES ON THE 335 TAKE TURNS RELEASING EXHAUST FUMES. tHE AIR FUEL MIXTURE MIGHT GO LEAN OR RICH AND CAUSE YOUR CATS TO BURN. TRUST ME I KNOW
How do you know I might ask? The car is going to release the same amount of pollution no matter which muffler/s is active or not. The cats are pre mufflers so the gas goes by them before it even touches the mufflers. I don't see how it could have any effect on the cats.