i sprayed liquid dynamat, tighted the bolts, then added dynamat sheets to my old camaro and it worked fine--no rattles. i had 2 l7 10's, ported running off of a kicker 1200.1.
99 M6 t-top leather silver/pewter Z-28, 408ci, 471hp, 465tq
09 Diamond White Escalade
2013 Glacier White Audi S5