welding braces to rear deck?

I am hearing loud vibrations from my rear deck. I applied RaamMat to it, and it fixed it... for a week. Then it came back. I couldn't figure it out, then my brother looked at it, found a spot in the middle, pushed down on it, and it went away. Pushing down on it, you can really see and feel it moving. I was thinking, maybe some metal rods welded to it would act as braces and simulate someone pushing down on the deck (i.e. keep it from flexing/moving). If this is true, please give me some pointers on how to weld it, and what kind of metal. Thank you in advance.Jon

Don't like rockford subs? Then don't look at my car =)

JB weld would be a bit easier. not sure that you would want to

Find a place where the rods would not flex and run it across it to another loaction thats stiff and wont flex. Then add another layer of mat.

I need quality equipment, feel free to donate.

Thanks Maxst, that seems like a good solution, especially since I can't find anyone with a welder. Any recommendations on what type of metal might be best?Jon

Don't like rockford subs? Then don't look at my car =)