Wow! That's a project! I'm my 2014 Vegas, the "ceiling" above the engine, under the dash was not sealed well at all and I spent a lot of time and effort sealing it from the bottom. In my 2016 Axis, the "ceiling" is all one piece and when I put insulation on from the bottom, I did not find any gaps like I had in the 2014. Even without the gaps, the noise reduction was significant. I can imagine your solution of taking off the dash and applying it from the top would be much better. I can see my wife's face if she found me with the dash all apart! As far as five start tuning, I can say that the difference in noise level between my old 5 Spd and the new 6 Spd transmission, both without five star tuning, is considerable. I love the new 6 Spd. This is the third V-10 I've owned.
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