Mine had the Kinetik sunk in flush and was done to support the amp rack and the second level was done to sustain the weight of the subs..
when removed for racing it was pretty quiet in there. Then again I have alot of Dynamat. Performance gains where only noticeable in the quarter as far as weight loss goes. In total with the sytem in I am 640 lbs over stock curb weight. With out the system and several other things ie., door panels, carpet, head liner, rear seats upper and lower, read deck lid, spare tire, B pillars, C pillars, seat belts in rear, and about 15 sq. ft. of sheet metal removed that I deemed un necc. I was close to 2100 lbs with the driver and enough fuel to make it to the end of the track and back.
Do the math at 100 lbs = 1/10 sec.