Our 2015 has always had more of a growing sound than our 2010. Our 2010 is my dailydriver, so I've not gotten so accustomed to the 2015 that I don't notice it. The growl in our 2015 seems the same to me as before, and my wife, who drives the 2015 daily, hasn't remarked about any change in sound. If it were my daily driver, I wonder if I'd be overanalysing its sounds. I've done this with modifications I've done to cars in the past.
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On my 25 mile commute to work this morning I really tried to observe any impacts from the fix.
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MPG's according to the MDF seemed to not have been effected. Around 47 which seems to be around average. As far as that "push you in the seat" feeling I really could not tell it had changed. You have to be right in that sweet rpm range to feel it, but it's always been like that.
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I suspect that if you do mostly start and stop driving your DEF usage may increase, highway driving not so much.
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So in summary, no noticeable effects for me. It just may be that my senses are not as keen as some. Some say they can tell a difference in performance when they change their oil.
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However I do think it sounds slightly different, but like you said maybe that's just because I never paid attention. As someone here speculated, it may be related to the DEF dosing.
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Bottom line. Sassified. Should get me email in a few days.
I want to thank everyone here who offered feedback from the phase 1 fix. It helped me decide to keep the car and take the restitution cash.