GR Yaris Sound deadening

[DraPPer]

Hi all, trying to understand the possibilities for sound deadening in the car. Using mainly for track use but given that I usually commute at least 400-600km back/forth to the racetrack, the trip in the Autobahn is becoming very tiring from the noise only (noise cancelling earphones help a lot but if I travel with a companion cannot use plugs or earphones).

I have ordered 3sqm of Killmat and same for self adhesive sound insulation foam (eggshell).

- Current weight of the 3sqm Killmat is 8kg, do not plan to add more than that since I am - relatively - mindful of the weight (plan is at some point to get a light battery so offsetting each other)
- Having semi slicks clearly road noise is something unavoidable but booming effect at the back is irritating
- Aim is to use as little as possible but enough to make an impact

Before I start I'd like some info from people who have already done it or have experience (especially given that removing it seems to be quite a hassle if I regret it):
- Plan is install Killmat at the rear boot and side (not door panels, not rear sides, not front/rear wheel arches and not removing rear sits, carpet, etc)
- Is the above enough or waste of time in terms of impact ?
- Is the Killmat alone fine or adding the insulation foam helps ?
- Could the insulation foam alone make a difference (cheaper, easy to install/remove) ?
- Do I need to cover every possible space in the rear trunk or placing large panels where they fit is ok with some uncovered area remaining ?

TIA for any advice

 

[YeahButNoBut]

If you're not planning to do the (inside of) the doors, back sides and wheel arches, then from my experience it will not make a difference that's worth the effort.

To be fully transparent, I've not done this on the GR Yaris (yet), but on plenty of other cars I did. Many years ago I went completely crazy on my F56 Cooper S, doing the complete interior. Door cards, carpets out and everything. But even then I was not impressed by the difference in road noise after the job. The sound system improved significantly though as well as door closing sound and rattles. But that can be achieved by doing the doors and door cards only. To improve road noise, I was never too impressed, even with doing a complete interior.

 

[GRgrampa]

I soundproofed the areas you are thinking of doing mainly to reduce exhaust drone. The car was already fitted with an HKS Spec L when I purchased it and it got on my nerves. Whilst it helped reduce the exhaust sound it did little else in the way of making the car quieter. I think personally this is a case of all or nothing to be effective.

 

[MrJ]

Mine’s a daily and I found it makes a big difference, I also have the HKS Spec L fitted. The thing to remember is it’s damping the resonance of the panel rather than soundproofing, and in that sense you can make quite a difference adding pieces (I used Dynamat) onto panels that are going to transmit and amplify road noise.

You can get a good idea of this by tapping the panels with your fingers and seeing whether it’s a thud (good) or a clang (bad). The boot floor, rear arches and quarters, floor under the rear seat, and a little on the inside of the door skins made a noticeable difference for me.