Dampening ALWAYS helps trunks and this is definitely true for WRXs. Its a big tin can

I'm not saying it will eliminate it but it will reduce it. You probably need to go through and check everything inorder to stop the rattling. Check behind your license plate, body panels, rear deck (this definitely rattles), etc.

 

I have Dynamat Xtreme (on my trunk lid) and a Dynamat license plate frame (I have a Eclipse 10" bandpass box). Not only aren't there any rattles audible from the outside but the trunk closes with a really nice thunk, it doesn't sound cheap like it did stock.

 

i have a 97 outback with 2 audiobahn 12's on 800 watts. I had a hell of a time with rattle and found that it was a component of the trunk handle opener lever thing lol...i put some dynamat in...increased the bass but didnt really change the rattle

 

some of that rattle might be coming from the rear deck as well as the trunk. if you dynamat, you might as well do both. i dynamatted my trunk (did not do the trunk lid) and still have a few minor rattles. the way i see it, subarus are never going to sound like audi/bmw's unless you spend an excessive amount of time (and money) dynamatting, wrapping wires, and insulating odds & ends behind the panels.

 

I had a small miniscule rattle. l took out all the carpeting and put 3m padding tape (like used in sports helmets) and i padded every corner that was hitting. No rattles and fits great. Good luck.

WRX Rush

 

When I started my system EVERYTHING buzzed. I dynamatted the fenders, trunk lid, floor and rear deck. This helped a lot but the worst was coming from under the car. I used some spray damping to coat the underside of teh spare tire well and the inside of the bumper. Again, better but not perfect. I need to find some sort of pink noise CD so I can go back and hunt down the buzzing for good.

 

the car is factory noisy and i think to buy Dynamat mats in the entire trunk to avoid the sound and in the road noise.

 

Dynamat works really well but before you put that down they sell spray stereo foam. You just spray the stuff between panels and cracks and then put down the dynamt in your trunk on top of it. Works perfect everytime.-Todd-