i have used 2 gallons of 'sludge',first impressions are very good, i did the whole trunk and trunk lid in about 1.2 gallons. and did the front doors with the remainder.i put a super heavy coat on everywhere with rubber gloves, no brushing just gooping, went on easy, took about 2 hours to to everything (cant see me acheiveing that with matt)gooped it on the outer skins of doors outer side of inside skin and inside skin.just gooped it all over any bare metal tried for about 3 mil but probably varies between 1 and 8???!!!! depending on access. its been 3 days now and the chits still wet !!! the reduction in road noise is significant, my car is a mazda 626 1989, its a metal drum with wheels! as i went over the trunk 'tapping' everything resonated badly.but no more. i only just put the sub back in and havent driven anywhere yet so ill report more in time and as it dries. but for $100 (b stock 2 gallons + shipping) and 2 hours of my time, im seriously happy with the results.i can see me ordering 2 more gallons and doing the floor and rear doors very soon.im fairly sure if i did that my pos car would feel like a merc?