I used to do high end stereo installs that focused on sound quality (I didn't waste my time with the boomers) and I can say that dynapad works as advertised. There are other manufacturers out there Boom Mat and Image Dynamics come to mind but I have stayed with the Dyna- products because I know they work and install as advertised. I have two rolls of Dynapad in my garage right now that will be going into my rig as soon as the ice melts a bit and I find time to make the changes. It will kill heat transfer and helps on engine and road noise transmission but it isn't a cure all. You have to add in some dynamat on some of the larger flat surfaces to cut resonance. Covering about 1/4 of a flat panel with dynamat will do the trick. However, if your floors are wood, which on most As they are, then you can skip that step. Wood doesn't resonate like metal does. Once the floor is covered, folks that drive Cs will start to notice the road noise from your doors and windows. Dynamating the doors will kill the resonance. They sell door kits for the purpose for about 70.00. It takes about 4 hours with a rubber roller and a hair dryer to do your first door but after your first your next will be substantially easier and faster.
So what do I expect from my winter work? Your ear perceives a 3 decibel drop as about a 50% drop in noise reduction. Realistically I expect about a 3 to 6 db drop in noise levels. 3 db if your insulation was standard automotive grade foam insulation and 6 db if your insulation was only partial like it is in many of the class Cs. If you pull up your carpet / rubber flooring and see a heavy 5/8 to 1/2 inch thick solid pad that weighs 1-2 lbs per square foot then it might not be worth your time to replace it. However, very few cars have that level of insulation (think BMW / Mercedes / Lexus) so I doubt most rigs have it as stock insulation from the factory but some Diesels might. Please note however that the pad and mat won't eliminate the noise, only reduce it.
If you are dealing with an engine cover and don't want to mess with removing the interior covering then maybe adding an alumminized insulation to the inside of the cover might be a good first step. I skipped that step because the factory already did a bang up job insulating the dog house on my rig but if you're driving an A it might be worth a check.
Dynamat.com | The Hoodliner for Automotive and Restoration
Regarding the 5star tuner. When I spoke with Mike he warned me that starting some time in 2012/13 Ford added a software patch to detect tuner alterations even when the computer is returned to stock. When you flash the program the ECM stores a code indicating that a non approved update was installed. If you have a warranty claim against your engine and they find that code stored they could deny the claim. However, Mike also said that he hasn't heard of anyone having any troubles with a Dealer when using a 5 star tuner. Still I decided to wait until my warranty is up some time next year.