what color is the smoke?
You will smell exhaust burnt fuel(white smoke) pretty much all day with catless dps.
It's a different story if it's burn oil smell (black smoke).
2008 335xi AW/Black MT
Avant Garde M359 l Hankook Ventus V12 l Kw V1 l M3 Front+sides | Mtec Rear | LCI tails l Cobb Stage2+FMIC l AR DP l ER IC l ER CP l Tial BOV | AFE Stage2 DCI