I love my Stillen Gen2. It doesnt get very loud unless you want it to, but it sounds fantastic. I never notice any drone but it has a nice low sound with good range. Its 2.5" dual piping all the way to the muffler and its got an X pipe. Very well made exhaust and fits nicely, even on an AWD sedan.

from my personal experience...based on a scale of 1-5 of loudness/drone

stillen gen 1 would be a 5
stillen gen 2 would be a 4
HKS + coupe midpipe would be about a 3
Borla would be at a 2.75
G35 coupe stock would be at a 2.25
05-06 stock would be about a 1.75
03-04 stock would be at a 1.5
my moms camry would be at a 1

this is all from my memory of hearing them all in person for your own reference only...I dont have a db meter in my brain okay....

I love my HKS exhaust!

https://g35driver.com/forums/media-share-g35-sedan-v35/211941-mod-2-hks-exhaust.html

I have a greddy y back and i love it

Go big!