So I put a Japspeed rear box on the back of my 5, and it is a bit on the boomy side, so I got some silent coat (£25 for a pack of 8 sheets and a roller), and the results are fantastic, what a difference it makes, I can now hear the exhaust and the engine, the resonance has been dulled down loads and I am pretty happy with the results. I also stuffed some old towels into the cavities either side for good measure. Before I did that I blocked off the sound tube too. This car is coming along nicely!
I wouldn’t have put towels in, they are made of cotton and cotton absorbs moisture. Can you find a better less absorbent material, loft insulation would be better perhaps?
Did my boot a couple of years ago, and as the interior was out did that too. Made all the difference. Now a nice sound from exhaust, but even better when the stereo is on only music.
Once again a sponge soaks up moisture and hangs on to it, sitting wet next to metal panels or wet lumps in your boot not a good idea. You could try to get closed cell sponge.
They do say it’s good stuff. When I was youth I wanted to dynomat my car to stop rattles from my audio (chav speakers haha) but couldn’t afford it, I used some thick roofing felt instead. Was very cheap it did work. I have no idea how much better real stuff would have been but the improvement was undeniable. I guess the extra weight and softer material just made it harder for the metal panels to resonate and produce reproduce noise.
Might look into doing this to mine now. Good call.
What is amazing is this silent coat apparently uses military tech and turns noise into heat - which I can confirm when you have a feel it after a drive - so you can stick a chicken in there for a long drive and have some a hot meal when you get home!
Probably right - I’m just regurgitating the sales pitch that I read - I had a bit left over so I have also stuck some to under the rear valance (sticky side facing down) and above the pipe tip cowling to see if that takes away some of the very low rpm roof down resonance that there still is, that thin flappy rear assembly has to resonate and contribute too, I would have thought.
