Exhaust sounds "throatier" on long trips?

[sparklesTHEpony]

I have a stainless exhaust from cat back with no middle section. Exhaust is pretty loud to begin with but I've noticed today and on a different occasion (2-3hour trips) that the sound dramatically increases on the trip back, sounds a lot throatier/Meaner with quite a lot of popping. Not pops and bangs remap pops but a more of a crackling sound.

is it something to do with driving for so long or what??
Just come back from a long trip now. The other time the sound worn off and went back to the original sound after a couple of days. It don't seem to be permanent.

Theres one other thing aswell. On both occasions on the way back the only petrol stations I can seem to find are shell ones. Fill it up good from almost empty and it begins from there? Not the V power stuff either I'm only running a 1.4

anyone else notice such things or am I just losing it from sitting in the car for too long.

edit: I never ever use shell. Just sainsburys or tesco juice.

 

[da rok]

my exhausts tone seems to change slightly depending on temperature, however im sure losing it from sitting in the car too long is also a viable answer

 

[Fletcher]

Mine gets slightly louder after a few miles too.

 

[Kazumz]

The noise is produced somewhat from heat so the hotter the exhaust the better or more different it will sound.