Hey guys, dod i search before posting. couldnt find anything related.

So the exhaust noise at a cold start is normal. we will use this noise as baseline/control for me.

I have moved to ABQ NM and the barriers here, or the change in alt, has allowed me to hear the same, cold start exhaust noise, at low RPms during acceleration.

Not sure if i am just paranoid, but I have confirmed this through multiple days and testing.

The car is warm, still hearing the noise even after driving for 10+ minutes. I can hear it during acceleration, stop to 3k. not sure if it is continuing after 3k.

I do notice the "cold start exhaust noise" in tandem with the appropriate exhaust sound post muffler, essentially the true noise we love, esp when vvt (or whatever our version is) kicks in. i.e from the driver side, I can hear the cold start noise on acceleration on low rpms, but also the smooth exhaust sound comming from the rear.
Also, have noticed, I cannot reproduce this noise in park, only when accelerating

seems to be something equivalent to an exhaust leak somewhere near the motor, possibly converters? if they go bad, would they have the harsh noise up front and still give the smoothness in the rear?

stock exhaust. plan on replacing for ark, but if it is the converters, may see about waiting until test pipes and exhaust
2013 G37xS 38k miles

thank you in advance, I hope i was able to communicated properly.
please let me know if you need clarification

 

ok an exhaust leak will sound like helicopter blades.

i am not sure what you mean by "cold start exhaust noise." like do you mean how it runs a little rough and the rpms stay high?

have you checked to make sure all your exhaust heat shields are not loose and all the connections are tight?

take a video. it will help us, help you.

 

yes, the "cold start exhaust noise" is the known issue with the exhaust valves needing a moment to correct/adjust timing, which makes the diesel like exhaust sound at cold start.

I am unable to take a video, as it is frowned upon to drive and operate a phone around here, but I will see what i can accomplish. The exhaust sound is only reproduced under acceleration, not at parked and revved.