Low end build, sound deadening.

In addition to/On top of what has been said, perhaps the Walmart bed liner on the floor board first. If it has been sitting awhile, there isn't much non-skid traction stuff suspended in the liquid. $45 gallon

I got some stuff from work called sikoflex- it works great but the navy paid for it, mixed too much and I drove home and poured on my floor pan. It was thick like caulking. The boss said it wasn't expensive. It would be fantastic under your car.