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Anyone think the engine sounds wretched from a cold start? I have added the Dinan exhaust system which obviously adds slightly more volume and exacerbates the problem. Trying to sneak out of my neighborhood in the morning is difficult.

I know it has to do with the way BMW warms up the engine. It opens the valves in an attempt to get more fuel through the engine and into the exhaust. An attempt to heat the 02 sensor I would guess? Any techs think adding a valve to partially block the exhaust though the warm-up phase would cause problems? I know this would reduce volume and probably change the tone considerably but I would think it would also help heat up the system. I am not sure if it would set off engine warnings tho?
 

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too risky
Have you considered those car engine warmers people use in Minnesota and other cold places? It might keep it warm enough to get quieter quickly if not initially
With my Dinan exhaut and Evo headers I'm quite loud for about 45 secs then somewhat loud for another 60 before going to baseline ( which isn't quiet) I found that gentle constant throttle and keeping under 1600rpm keeps it quieter during warm up.
 

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