128i Secondary Cat Delete

[christian_128i]

Currently, I have the Magnaflow Cat-back Performance exhaust on the car, and it will be 2 years this spring since it was installed.

Before chopping up my secondary cats, I was open to any suggestions anyone had with a similar setup.

I was wondering if a secondary cat delete will even be worth it with the current setup I already have and if it will be noticeable.

Feel free to drop any shop names in the Toronto Area, that are trust worthy with this line of work!

[golfer23rm]

i have guttered the cats, but stock resonator and stock back box on a 125i Auto. I have done the bimmerlabs 130i tune and 130i auto gearbox tune. The reason i stuck with the stock back box and resonator is when i did the golf tee mod, i noticed a drone and this was with stock cats.

What i did do is i put mini cats - cat foolers on. Before the foolers the car would smell a bit rich at times. You also get cat errors but they do not affect performance.

[Olgeezer1]

The secondary cat delete gives a small but appreciated slightly deeper sound. My exhaust is otherwise stock, except for the golf T mod. keeping both pipes open. One benefit of the secondary cat delete is the removal of a pretty major restriction in your system. Looking at my cats once removed makes me wonder how anything gets through there. There's a slight H.P. gain and others report slightly better mpg. Any competent exhaust shop can cut them out and weld in some straight stainless pipe. There's no downside.

[Blau]

Originally Posted by Olgeezer1

The secondary cat delete gives a small but appreciated slightly deeper sound. My exhaust is otherwise stock, except for the golf T mod. keeping both pipes open. One benefit of the secondary cat delete is the removal of a pretty major restriction in your system. Looking at my cats once removed makes me wonder how anything gets through there. There's a slight H.P. gain and others report slightly better mpg. Any competent exhaust shop can cut them out and weld in some straight stainless pipe. There's no downside.

Just be warned, not every shop will do this job. Secondary or not, the cats are an important part of the clean air act. In many states it's also illegal to remove them and the shop and car owner can be fined.

I want mine removed, but don't want the trouble of re-fitting them every two years when I go for inspection/ emissions.

[Olgeezer1]

Originally Posted by Blau

Just be warned, not every shop will do this job. Secondary or not, the cats are an important part of the clean air act. In many states it's also illegal to remove them and the shop and car owner can be fined.

I want mine removed, but don't want the trouble of re-fitting them every two years when I go for inspection/ emissions.

True as you say in some jurisdictions . Was originally for the California market but BMW figured might as well do it for all North American cars. Overkill really but luckily for OP and myself that problem does not apply.