After two+ years of tolerating the IMO sub-quality audio emitting from the OEM speaker set-up in my 2018 AIGT EXT, in March of 2021 I replaced both the front door panel speakers and the two rear coach speakers. I DIY'd all the work for it was not that difficult, just a bit tedious and time consuming.
Installed the same speaker at all four locations. I posted a brief write-up on the rear coach speaker install that I've referenced below, along with the product link to the speakers and a few other ancillary items.
When installing the front door panel speakers I unhooked the small tweeter speakers in the upper dash corners. I may have been fine leaving them connected, but since the replacement 2-way speakers I was installing had a tweeter, I did not want to risk any of the new speaker audio competing with the OEM tweeters and it maybe sounding odd. End result; these Rockford-Fosgate speakers sound excellent, good highs, good lows and everything in between. Plus they can easily handle those "oh I wish I were 25 again" moments when you might dial-up Van Halen's Eruption and turn the volume up high!
While I had the front driver and passenger door panels removed for the speaker install, I went ahead and applied Noico 80 mil Sound Deadening Mat. This is a foil clad butyl automotive sound deadener for the purposes of audio noise insulation and dampening. It's a very dense peel and stick product that was easy to work with as the objective was to apply it to all of the inner door panel's metal surfaces. I was extremely happy with the level of road noise reduction in the cabin area of the rig this product provided and now when you slam the door, itís more of a solid "thud" as opposed to the hollow/tinny sound from the OEM set-up. There are a lot of similar peel & stick noise dampening products available, but this Noico product worked fine for me.
If you choose to tackle replacing the front door panel speakers you'll inevitably break multiple mint green colored door panel clips...buy a bag, you won't be sorry.
Additionally there is a spacer/adapter ring that is required for installation and proper fit of the two 6 1/2" front door panel speakers.
Rockford Fosgate T16 Power 6" 2-Way Coaxial Full-Range Speakers
NOICO 80 MIL NOISE DEADENING MAT
DOOR PANEL CLIPS
SPEAKER ADAPTERS FOR 6.5Ē SPEAKERS TO FIT 2007-18 SPRINTER NCV3 CAB DOOR
REAR OEM SPEAKER REPLACEMENT POST