Recently put a new aftermarket exhaust on my 2010 Sedan and I’ve found that it’s been banging on the support that would normally sit under the Y pipe. Wondering if that support is structural and if removing it or grinding it down to limit noise is an option or if that would compromise the rigidity.

 

All you need is a few mm extra clearance, so get out the crowbar and bend it. Or remount the bracket with a couple of flat washers. But don’t delete it.

 

So this bar offers .5 to 1% of body rigidity. It's meant to catch the exhaust in case of failure.

You should start with Rochester's approach and bent it since it's pretty thin. If that fails you can take it off and will be fine.

 

I had some exhaust hangers that needed to be replaced and drooped my exhaust some, I would get vibrations via contact like you're experiencing. Removed this brace, block of wood on each end of it, stepped on it in the middle a bit, bolted back up, and good to go.