I found that the rear door seals made the most difference and as others have noted, it’s usually at lower speeds up to ~50 mph.. on the highway, it’s all about tires, tire pressure and the front light boxes.. mine had a big lip/gap that was raised up. I put just a tiny bit of clear bumper guard on them around the lower portion and it really reduced highway noises from that area. I have read that there is airflow disruption around the A pillar from the bonnet corners to the A pillar box.. putting some spongy form in there apparently works to reduce this airflow congestion, but I haven‘t tried that one yet.
Newer kits come with frunk and truck seals too, which I don’t have . I can only imagine that might add a bit more soundproofing or else they wouldn’t include them.. although we all know the problems with the M3 trunk and water coming in, so maybe that is a bigger reason to include them. At some point I’ll add these extra bits and see.
