Sound deadening & rear cab delete/mod

Hi all. I'm just starting the rear seat delete in my 2021 Access Cab and thought I would share a few photos as well as ask a question.
The top photo shows the "sound deadening" behind the rear seat backs (if you want to call it that). It's a piece of light weight felt that might be 1/2" - 3/4" thick which is different from what others have posted. May be a Canadian thing or maybe a build date thing. Who knows. Not quite what I was expecting and I didn't think that it did much.
I was a bit off on that assessment because after taking everything off and then going for a spin, it sounded like the back window was open or missing or that there was a huge hole in the back wall
Turns out there are 2 pieces of plastic (circled in second picture) that don't really have any purpose that I can tell.
My plan is Dyna Mat & then foam/MLV product from Second Skin the back wall and back floor pan. Then replace some stuff or build a platform, not sure yet. It's/I'm a work in progress
So my questions (maybe more than one ) are:
What is the purpose to the plastic pieces?
Has anyone ever taken them out, can they be taken out or is it a good idea?
Or have you just put Dyna Mat then foam & MLV over it or whatever your process was?
Thanks and I'll share the photos as it goes as well as a few other projects that will start soon. Waiting on the warmer weather.
Cheers!

 

Those let the cabin pressure equalize so when you shut your door with the windows closed or get in an accident and the airbags deploy it doesnt shatter the windows or your eardrums not something you want to remove. You can put some padded foam over them to help with the noise, while youre there i would silicone around the vents they are known to leak and let water in the cab

 

Nyrob, thanks for this Makes sense and I appreciate the suggestion of siliconing around them.

 

I removed everything, ran butyl deadening + closed cell foam over everything in the back.

I did cover those flaps, then I cut slits in them so they would still "work".

I went with Noico for both.

 

I'd suggest in a addition to what you are doing putting a pool noodle or piece of pipe insulation between the cab and bed. When I put a 3/4in piece of pipe insulation it was less than $4!

 

Thanks Sand_In_My_Taco. How were the results and did you do the floor as well? Just curious, did you silicone around all or part of them as Nyrob suggested?

 

Squirt, where about did you put it and did you notice a difference? Thanks for the suggestion.

 

Just go underneath the truck and shove the pipe insulation between the cab and bed. Theres a little bit of a lip on the bed that holds it in place. Just check on it occasionally to make sure it doesnt move. I sound deadened the floors, rear wall and doors in my old Taco and this made a big difference and was the best bang for the buck and took 5 minutes!


Pro tip!! Do it when the truck is cold as the muffler is below the gap!!! Don't be stupid like I was

 

Great idea!! Nice work on the back seat area as well. Thanks for the pics.
I’ll take your advice and add it cold Easy to do here in the north

 

Thanks
I did 3M sound deadening with Frost King HVAC insulation over the top.

After I got my current truck I did the floors and rear wall with 2 layers of the Frost King...

 

What does this do?

 

Helps with road and exhaust noise for cheap.

 

Awesome. Thanks so much for the explanation.

 

I did not silicone, I also had no leaks.

I did not do the floors.... Yet

I also need to do the roof.....

 

What kind of debris build up, if any, are you getting on the insulation? Looks like you have a cap, possibly helping keep some debris out?

 

When I had my Taco I didnt have any to speak of but then again it was a pavement princess. There's enough of a gap you can spray in there I'd you wanna rinse it out

 

That's good to know. Everytime I have the passenger seat down I feel like to need to look back to verify I didn't develop a hole in the back! I am slowly collecting the supplied to do some sound deadening. First priority is swapping out the bed rack for the cap though. Then I hope to get to it, and may finally install the heated seats after failing to for two winter seasons...

 

I may silicone the bottom half. Not sure if I'm doing the roof, we'll see how doing the floor and back wall works. Stay tuned

 

For the price I'm going try it and see what difference it makes. Mine goes off road but easy to take out if it becomes an issue.