Originally Posted by CJ421
I personally wouldn't say it's normal; my AR 4" has been on for almost a year and the car has not acted differently. I have a JB4 (map 2) as well. Mine is a manual transmission, not sure if that is related.
When I had my berk 4" downpipe. I never had any problems either.
Current: 2013 335i 6mt msport
BMS Clutch Stop, JB4, ER Downpipe, ATM FMIC, ER Chargepipe, aFe Momentum PRO 5R Intake, aFe Air Scoop
Past: 2011 335i coupe
369 whp/444 torque. (Procede
, Custom Turboback Exhaust, BMS Intake, ER FMIC)