I stuffed cotton balls in my vents to stop them from rattling. No rattle and no leak (if infact that is where the water is getting into your trunk).

1999 Contour SVT #1966/2760, Silver Frost/Midnight Blue Koni Kit, Mille Miglia MM-S rims, B&M shifter, Stazi mesh, SFCs, optimized Y-pipe & TB, SS break lines, K&N drop-in, Infinity Kappa speakers, MTX amp/sub