My car makes this ratteling sounds under neath all the time, It sounds bad. It usually happens when I let off the clutch to much without enough gas or I put it into reverse, or even If I walk around the back of my car. My friend said it was the "h-brace"? Anyone know what that is? Is it serious? I'm about to make my car alot faster and I want it to be safe!

 

check out all your heat shields first. My car rattled like a bitch when i first got it, and when i installed my catback i ripped out all the heat shields....no more rattle

 

hmmmm, that might be it. . . .thanks! By the way, is their such thing as an h-brace? I swear I saw one on e-bay.

 

Yes, there is such a thing as an H brace.