My butterfly valve is always open at idle but then closes if I accelerate moderately to alleviate exhaust noise at the mid-level RPMs. If I accelerate quickly it stays open the full way. My exhaust note is quite noticeable at idle. I am still waiting to get performance exhaust on the next one.
'08 Sparkling Graph. E92 335xi (ZSP w/ 18s | Saddle Br. | Grey Poplar) (Returned)
'11 Space Grey E92 335xi M-Sport (KWv1 Coils | Saddle Brown | Bamboo) (Returned)
'14 Mineral Grey F32 335i M-Sport (Dinan DHP | LED Lights | Coral Red | Hexagonal Aluminum)