Got a 440i gc w dual res delete. Just got mhd aswell and want to start pushing some power. I do prefer the sound of catted with the deeper tones compared to the loud raspy catless. However i also like that i can shoot gunshots with catless without worrying abt blowing cats, cause there are none. The smell is manageable sometimes… prices are completely different, catless is abt $300 cheaper. just want to know if i do go catted, am i safe to run soft or medium burbles or just not burbles at all. Is one more worth it than the other? I do want to push power but nothing excessive, still want the car for longevity. Ive also heard burbles are not good for the turbo( any truth to this?)
Went with catless on my F10 535i… Unfortunately if you daily the car the smell is quite unpleasant (feels like/worse than a diesel). So I sold it and bought catted one.
My personal recommendation is to go for catted high-flow downpipe. There is still some smell, but significantly better compared to catless setup. Works very well on Stage 2, 2+ cars.
If you go all out for 500hp+ mods then catless makes sense. But I always like to think that stock 500-600 M models have cats too, so should not be a problem in general if the cat is right.