Simple Sound Tube Switching "on/off"
 

So how many of you don't like the "induction sound" heard inside your 86?

Pictured here is a plastic cap that is the exact right size and pushes into the rubber pipe just above the pedals. (on a RH drive car) Pull back the stock mat and you will see the tube.

Install time 10 to 12 seconds. This little beauty kills all the sound stone dead! All you hear is the actual engine sound coming from the engine bay, just like any other car. Also with a TRD exhaust you hear a bit more of that, because it is not drowned out by the induction sound in the cabin. On track day, simply pull it out if you want the noise back.

The inside diameter of the plug (the important bit) is 22mm. The outside (top part) is 27mm, however that dimension is not really critical. The beauty of this idea is it requires no tools. No glue. Nothing..... just a plastic cap for about 20c. Simply push it in and it will stay there. If you live in New Zealand these can be purchased from Hi Q Electronics. Elsewhere... I don't know, but it works brilliantly!

!!!UPDATE!!! ADDITIONAL IMFORMATION SINCE ORIGINAL POST!

@enouf has discovered that you don't actually need to buy the plug I have used. You can use the 12V adapter cover that is in everyones glove box. I have verified this by using the one in mine and it works great. So now this mod is not only one of the easiest and efficient mods you can do on the 86, but now it is also totally free!!! Thanks @enouf for bringing it to my attention.

Great tip. Thanks. That was the first thing I eliminated when I first bought my car. In all the surveys the manufacturer has asked me to complete I blasted them for installing the growl tube. I told them the cost of installing that would have well paid for the cost of a good cover/arm rest over the cavity in the center console.

for anybody in the US interested in doing this. i just took a quick trip to lowe's and found what i think is the same exact plug that @Tech used. it was about $1.50 for 2 plugs. fit perfectly. i'll see if i notice any difference when i go out later.

https://dl.dropbox.com/u/71070185/photos/mods/plug1.JPG
https://dl.dropbox.com/u/71070185/photos/mods/plug2.JPG

Yep that's it alright. I guess I have the price advantage because I buy these in bags of 100 for a product I make at work in my electronics business, but $1.50 is still very reasonable. I definately like the more natural sound coming through the firewall than what that tube produces. However I will be doing a track day this coming weekend so will pull it out. I will be able to hear what the engine is doing better when wearing a helmet. Then plug it back in for the trip home.

So I'm just curious, but what did you do with the other portion of the sound tube? Did you use something else to plug the intake side?

can you do the opposite of this to make it louder i love the sound

This mod is only for people who do not wish to delete the sound tube, but want to suppress the cabin noise and be able to undo the said noise suppression whenever they'd like.

Sent from my HTC Rezound using Tapatalk 2

Thanks @Tech this is perfect.

I currently have the blue TRD "blocking" sound changer installed but will now look to put the "noisy" one in and one of these plugs so I can easily turn on and off.

In a RHD car installing the TRD sound changers are a mission with lots of stuff in the way so this is a million times easier.

The simplest DIYs are the best for me!


.

I'm guesing that deleting the tube entirely would still be more efficient. I can't help but think there would still be a certain amount of resonating from the fire wall.

There's not much sound left @whaap after blocking it.

I have the blue TRD "blocker" in and the cabin is pretty quiet now with just the nice exhaust note form the TRD exhaust.

don't think you'd make it much quieter removing the whole thing.


.

I didn't do anything to the other end. It is just a plug in the end of the tube. At revs above 6,000 there is a very slight noise, but hardly noticable. In my case the natural engine sound is the louder of the two and the TRD muffler has a better tone than the stock one, which you hear more of. Nice balance in my opinion and completely reversable if you do want the noise back. As for the other post, if you want MORE noise (shudder) then I would remove the stock sound tube which I beleve is tricky to get at on the other side of the fire wall. Pull out the foam inside the tube and reinstall it. That is basically all the red TRD tube is (which is the loudess) which you can buy (way overpriced set of 3). However I have not actually tried it. There are better ways of killing the noise, but none as simple as this and that was what I was after. Quick, simple, cheap and can be easily undone.

Just plugged mine ( LHD US version ). "Nylon Hole Plugs 7/8 inch" ( in case the picture goes way eventually ).
When I got the plugs at the hardware store last night I ran right out and tried to install this intricate mod, but it was dark and I failed to find it.
Ohnoez! There's this huge HVAC plenum right about where it's supposed to go. I tried feeling around back up there but couldn't find where it was.

http://www.eskimo.com/~johnsen/car/res_location_LHD.jpg

Took a break at lunch today, dug around a little more and discovered what I think is the proper location in a bit more accessible place, just below and right of the lower center plenum bolt.
It's obscured by the top edge of the carpet and sound blanket.

http://www.eskimo.com/~johnsen/car/res_revealed.jpg

The plug fits in the indicated hole, so I think I've got it for the time being. No test drive yet.

I did this last night and I'm surprised the difference it made. It's much quieter especially at freeway speeds. This made me realize just how stupid the sound tube is. One of my biggest complaints with the engine note was that it always sounded hollow to me (I don't know how else to put that) and this actually gets rid of a fair amount of that. Not only is the car quieter at cruising speeds, but I actually think it sounds better under full acceleration.

Glad you guys are not having any trouble finding places to purchase the plugs.