Exhaust Sound at Start Up

[AER86]

I just went to do the NPP fuse delete on my Z28 and realized that the previous owner beat me to it (explains why mine pops and gurgles so much). But now it leaves me with a question that I thought pulling the fuse was going to answer.

When i start the car for the first time it bellows loudly which i love, but there are times when after iv driven somewhere parked up and then start again, it lets out a much more meek purr when started. I understand cold starts are normally louder, but i had thought this might be because the flaps werent opening on the second start, but with the fuse pulled i guess they are always open, so why so much quieter on the second start? is it just purely down to the car being warm? or is there something else mechanical going on ?

curious to hear other peoples experiences.

[Coz3z3]

Mine seems quiet after warmup too. It’s not as loud as I would like it to be. I thought it was just me as the 1LE has headers. So figured I was just used to that.

[0stones0]

I would agree that 1st start up cold hits a little harder than it does after the engine is warm.

[MIKZ28]

It's the fuel mixture and timing. At startup the mixture is richer and timing is different because of the cold engine. Once the engine warms up the computer leans out the mixture and changes the timing which causes the quieter sound.

[Hda]

Does the Z have an air pump for emissions purposes?