Vibrating at feet. (98 z28)

[nerd4life]

Hey guys,

Awhile back I noticed, when I got on my car(98 z28) fairly hard, a pretty bad vibration at my feet. Well I dont know too much about cars, so I automatically thought this was my transmission. With 120k miles on it then, and around 145 on it now, I really babied it for awhile.

Anyways, at 120k miles I had a major tuneup on it done, and my mechanic told me that its simply the pipes below rattling against part of the car. Says I bent the hell out of one of the pipes running over something. I never asked, but Im assuming I bent the small flat part of my exhaust that is the lowest to the ground.

My question is, I still baby my car since it still does this, but has anyone else experienced this? Im putting it in the shop this week or next, it now knocks for a minute or two right after a cold start and I want to get that looked at pretty quick.

Btw, the only mod I have done to my car is simply a flowmaster muffler.

And btw, I really like the sound of the Edelbrock cat back system. Any con's on this system?