VB,
I use either used sound suppression ceiling tile or indoor/outdoor carpet under my multi level FasTrack Layouts, to deaden the sound when running more than one train.
Further I always screw my FT down, every other tack. Carr McMasters on the webb has all the screws you need for FasTrack and everything else, I use PH FL HD Wood SC Z/P 100 EA #4x3/4 and #4x125PFW1P 100EA, inexpensive, 90% re-usable and they work well. They also work well with my inner oval of MTH RealTrax
PCRR/Dave