Hi i have a greddy sp2 full catback exhaust. Lately after replacing my motor mounts and front lca bushings im noticing that im hearing a metal on metal grinding noise towards the end of my car where the muffler is. It happens when the car has been driven for more than 10 minutes, only happens after gassing after a full stop and goes away after a little bit. It never does it on the freeway at a constant speed. It does it more so if the road is a little bumpy. Usually i am used to hearing the piping hitting against the heatshield in the rain, but it's been dry for a while. When I turn the car off or put it on park and attempt to shake the muffler aruond I cant replicate this noise.

so my question is could replacing motor mounts cause more movement in the exhaust?

how can check to see where its hitting exactly- could i put some rubber or grease or something?

 

Thats nuts. Your replaced motor mounts should have reduced movement in the exhaust.
The only way I know to find whats hitting is with a buddy. Have him hit the gas a little bit until i replicates the sound. Then start looking for it yourself.

 

well the new motor mounts have helped when it comes to my engine wanting to jump when i start it, but as far as having a friend look- the problem is it only happens when the exhaust gets hot and when the road is sorta bumpy. i also have to accelerate hard - nothing was touching when it was on a lift. and the car is so low that nobody can see underneath when its in motion...
could grinding metal noise upon acceleration be some other serious problem not related to the piping?