[radio3]

I was just curious if anyone had experience installing sound installation in these cars and had an opinion on how effective it is. I’m a considering installing a nice audio system and just wondered whether or not the noise floor can be lowered in any way. In some cars acoustic treatments are very useful and in others they are a waste of time and money.

[MarcoZandrini]

I installed Road Kill sound insulation in the trunk. I installed on those sheet metal surfaces that sounded "hollow" when I tapped them with my finger. I used paper as the templates. It does seem to have decreased road noise.

https://www.amazon.com/Stinger-RKXDK.../dp/B001HHX606

[nearwater4me]

There's a dedicated thread on the M2 forum detailing what many did for sound insulation but lots of the methods involved restoring the deleted insulation pieces from the regular 2 series, so that wouldn't apply in your case.

If you do some search online, there's an extensive test data regarding different brands of CLD tiles.
General consensus is the butyl-based deadeners are more effective than asphalt-based products.

I have applied Dynamat on metal surfaces prone to resonating and then applied the acoustic foam on top.
Acoustic foam work as sound absorbing/decoupling barrier vs. the CLD tiles working as sound deadening material, so installing both on applicable surface will increase the effectiveness of sound insulation.

I did not do the floor as it involved extensive removal/reinstallation of interior parts, but just doing them on the door, rear cabin and trunk area made a huge difference.
Eliminating rattles while doing so by applying butyl tapes on the suspect area helped a lot too.

Obviously the M240i has more sound insulation material than the M2, so YMMV.
Hope this helps!

[TheSniper]

I've done the trunk, doors, and rear cabin.

It's made noticeable difference and I'm glad I've had it done.

I'd like to have the floor done as well, but it seems to be too intensive.