Im running Kenwood 70W 3Way 6X9's in my sails. With my Pioneer SuperTuner 45X4 in the dash. And my problem is my sails rattle like hell. All i can hear is the sheet metal vibrating behind my 6X9's How do i get it to stop? -Schwinny.

Are you sure its the sheet metal. If you open your door there is a black air breather thing mine used to vibrate like hell when the bass hit i just taped it off. But still could be your sheetmetal just an idea.

put some dynamat in the sail panels and on the black vent

Strange

Is the sheet metal glued or welded on (can't remember how it's attached to the inside)
Also another thing is, are the screws holding the speker in really good. I use to get some vibartion noise and it turn out they just need to be tighten every now and then. Even with the loose screws the rattleing was never loader then the music. If you won't mind putting up some pic of you rear speker area we could have a look.

keeslinger31 is right. Its probably the plastic air vent in the door jamb. I applied foam tape around the edges of the vent then re-installed. Problem solved.

It could be the vent in the door, or like in my case the plate that the speaker mounts to has 4 or so screws holding it on that get loose over time. The only way you can get to them is by taking the plastic out of the whole side and tightening them up. While your at it i would say throw some locking washers on them to keep them good and tight. Also i put rubber washers in between the speaker and the plate and that keeps the speaker snug against it without causing to much vibration.

Haha rattles in these cars are very promint without a stereo system of any magnitude. I have SO MANY small lil rattles from my system that I have plans to just do full heavy sound deading for the whole car. **** my wing that is bolted down very well flexes prolly a good 3/8's inch in the center or more when the subs are slamming. If i put a quarter on the t-tops it hops all over the place. Pretty much the bass is so loud i bearly notice the rattles till i go about 100 feet away from my car...even then you still hear deep bass and a few rattles(the back licence plate and bumper cover pisses me off!)

as everyone has mentioned, check the vents in the jambs.

also, if I remember correctly, there are some metal mounting plates for the 6x9s that mount to the pillar itself. Put some sound deadner between the plate and the pillar, may help fix the issue.