I just took my 23 Calligraphy to Ziebart to have their 4 step underside Sound Deadening, Noise Reduction Coating.
** NOTE 1: db Meter was help between the front two seats 12" above Center Console
** NOTE 2: Me talking normal was 67db - 70db
- Idling with car in drive mode: Before 43db - 43.5db, AFTER Ziebart - 40db-41db
- Cruising at 70 mph on asphalt: Before 66db-66.5db, AFTER Ziebart - 63db-64db
- Cruising at 45 on rough Concrete: Before 67db - 68db, AFTER Ziebart 62.5 - 64db
** NOTE 1: db Meter was help between the front two seats 12" above Center Console
** NOTE 2: Me talking normal was 67db - 70db