Hit Something, Oil Pan Trashed, Changed My Oil Pan, Now Cabin Noise/Vibration?

[brianpgriset]

I hit a random piece of rather large road debris a few weeks ago and it ripped off the front left corner of the oil pan. It was a pretty solid impact. I turned the car off away and all that, got a new pan on. I had to unbolt the engine mounts and jack the engine up 2 or so inches to fit the pan out between the motor and subframe, no big deal. Got it all back together and it fired right up, but now for some reason, I have a good bit more cabin noise coming from the motor now and I can't figure out why for sure. The noise is loud at certain RPM (resonance) and sounds like the motor is touching the firewall or something. I already crawled all around the engine bay and underneath looking for anything obvious but couldn't find anything. My muffler DOES have a leak, but I'm not 100% sure thats what is doing it since it didn't seem as loud before, unless a peice of the pan punched a bigger hole in it which is actually possible. It seems like the noise is from near the engine bay though. Can a leak at the muffler make that much nosie/vibration/resonace in the cabin? I just can't tell for sure what the new nosie is related too, the impact of the road debris, the new pan, the muffler, or something else I'm not thinking of.

I plan to fix the leak either way (any cheap, quiet muffler suggestions till I get a new exhaust?)

Some additional things I've noted or done that may or may not make any difference:
- The car is very slightly out of alignment now
- I also replaced the clutch master and slave cylinders since I saw I had a leaky slave, although I had the motor running before I swapped them and still have the new noise
- I am currently fabbing up a nice new skid plate that will put all others' to shame

[brianpgriset]

So thinking about it a bit more I think it is less likley an exhaust leak or a drivetrain issue since the car is no louder outside than it was before and sounds fine.