My apologies up front for doing lame teasers in multiple threads that were not my own across this board.
I have removed multiple resonators for several S63 Tu cars Ive owned and many Benzes, Audis, and even a Bentley with good results. My most recent resonator pull was on my M8 GC Comp and I gained a decent amount of decibels without much, if any, tonal change.
I picked up this G80 not too long ago and felt it was too quiet in stock format even with the valves open so I took it over to my local muffler guy who Ive used for years and pulled both resonators off. From another member here, I learned that there were two larger suitcases and pulling just the primary would not yield enough gains for me. YMMV.
So I pulled both (post cats) and there is definitely a decibel or loudness gain. I say under light throttle the gain is circa 20% and under WOT maybe 35% or so. Based on my live ear, the exhaust tones remained the same where there is a bass(y) tone at cold start and then a more higher pitched tone up top.
Mind you this process cost me 300 dollars all in and is reversible in nature. The video does have some higher rpm (7k) rasp but in reality I dont hear it via regular and spirited driving but you will hear it in the video from a stand still because I pushed the revs all the way up vs just leaving it maxed at 5 to 6k. For me the increase in growl and roar is there but for those who hate burbles, its not too bad. There are heightened bangs on rapid upshifts too.
Here are some pics and the vid:
stock set up
Post removal
Ugly secondary cats (Ill pull this next)
Cell Phone Videos (apologies for the bumper mount resolution)