Do you guys chase out every rattle or just let the trunk do its thing?

I went through almost the same thing in my old Civic hatch. Two 10s on a modest amp and the hatch glass buzzed so loud my ears read it as bass. One weekend I threw a roll of butyl mat on the inside of the hatch and the rear quarter panels, four hours total with a roller and a heat gun on hand. Night and day difference. The actual note came through instead of a bunch of plastic crackle fighting the music. The thing people miss is you don't have to do the whole car. The trunk lid and the plate area are ussually the worst offenders, so hit those first and see where you land. I added a layer of closed-cell foam between the lid skin and the brace on top of the mat and that killed most of the higher buzz that mat alone doesn't touch. Cost me under a hundred bucks and one afternoon of pulling trim.

That said, I get the loose vibe appeal. My buddy runs his Silverado with zero deadener and the whole cab shivers on certain songs, and he swears it makes it feel loud. For me it got old fast, because I kept turning the gain down to stop the noise instead of up to enjoy it. Once you hear the sub without the car joining in, going back is hard.

Funny, I went the opposite direction on my old Silverado. Had a single 12 under the bench seat and instead of tearing the cab apart with mats, I spent like twenty bucks on weatherstrip foam and felt tape and just went around killing buzzes one at a time. Door trim, glovebox, the little plastic clips behind the kick panel. Took an evening with the sub playing a low test tone and my hand on every panel until I found what was rattling. Cheapest tweak I ever did and it fixed most of the noise without pulling the interior.

Small pedantic point first, the gain knob is an input sensitivity match, not a volume control, so if the system was ever set properly you should be able to leave it where it is and just use the deck. On the rattle side, the plate is often the whole culprit by itself, and a couple of rubber grommets or stick-on foam pads behind the mounting bolts usually shut it up before you touch a single panel. One thing to weigh before layering mat on the lid of an older car, that stuff is heavy, and on mine the struts got tired of holding the extra weight and started letting the lid creep down, wich caught me off guard.

Been down this road more than once, and back in the 90s all we had was tar strips from the hardware store and roofing flashing slapped on with a putty knife. Ugly, smelled like a driveway in July, but it quieted panels just fine. The fancy rolls are easier, sure, but the idea never changed. One thing worth checking before you rip anything apart is the box itself. If it's a prefab with thin walls or a home build with loose joints, the box buzzing will fool you just like the trunk lid does. Push on the sides while it's playing. If the box rattles, no amount of matting the car fixes that.

Gotta push back on the trunk lid being the main offender, at least in my experiance. Did the lid on my old sedan first and the buzz barely moved. Turned out the taillight housings and the rear deck were doing most of the rattling, plus a loose clip behind the back seat I never would've found without pulling trim. So yeah, start with the lid if you want, but don't expect it to be the whole fix. I ended up chasing the noise around the back of the car for two weekends instead of one afternoon. The plate grommet trick from earlier in the thread is solid though, that one actually worked for me.

Agreed on hitting the lid first and calling it a win if the noise drops enugh. That's basially what I did in my old Accord, one roll on the lid and half a roll on the floor, and it took the worst of the buzz out. The funny part was what I found after: the jack kit loose in the spare wheel well was rattling harder than any panel, so I just wrapped it in an old towel and velcroed it down. Free fix, zero downtime. Also worth checking your tools and anything rolling around in the door pockets before you commit to pulling trim, loose junk masquerades as panel rattle all the time.

Update: went the cheap route first. Grabbed some felt tape and foam strip and spent an afternoon chasing buzzes one at a time, like the truck guy here said. Biggest win was the plate itself, two rubber grommets behind it and most of the fake bass vanished. Still gonna lay some mat in the trunk eventually, but it actually sounds like a sub now instead of a maraca.