Need Advice for my Rattling Roof

It's a 2004 Ext cab...

I just installed a stereo (sub) system in the truck, consisting of two punch subs and a punch 400.4 amp, bridged to the 2 subs. Head unit is an Alpine Vdrive.

First, let me just tell you that speaker design must have come a long long way in the last few years. I had two 12" JL's in my previous truck, but could not use them in the new truck since I need the back seat. So I decided to go with a pair of SAS tubes. The tubes had no speakers in them so I ordered a pair of Punch HE 8" subs to put in them.

While I was waiting for the 8's to arrive via UPS I put the 12's in the truck temporarily with the seat up. It was pretty loud. Just got the 8's yesterday and installed them. Without a doubt, they are much louder and clearer (cleaner) than the 12's. Even the low lows in the bass tracks are louder, which I would never expect from a pair of 8's, which leads me to my question...

When it's turned up and there is a lot of low frequency bass, the entire roof of the truck rattles or vibrates, and not just a little. It sounds like it's going to detach from the rest of the truck. Will dynamat help this? Any other ideas to get the roof panel to stop vibrating so badly? If you're outside and look at the roof it's deflecting about 3/4" to 1" in the center.

Thanks....!

Any ideas other than "Turn the radio down"? :)

Dynomat is an excellent idea. It costs alittle more, but I recommend the engine compartment dynomat. It deflects the heat alot more and with our black trucks there is alot. It will surprise you. Pull your dome light out one day and put your hand up there. Anyhow! Yes dynomat is the way to go. It has worked great on mine.