So, recently switched out the cat-back and I've been noticing that every time I let my car warm up it starts to leak water from where the mid pipe meets the cat. Pretty sure it's water, but it also looks like it has oil in it, but... doesn't smell like oil so i'm assuming it's just grime.

Is this normal? I replaced the old gasket with a new one that came with the exhaust.

 

Normal. It's condensation that has built up in the exhaust from sitting overnight, and as it comes out it picks up the exhaust soot that lines the inside of the exhaust.

 

This.
Is this your first car or something OP?

 

Your muffler bearings are leaking.

 

It's sounds like condensation to me too. Also the oil in the water thing could just be the exhaust residue in the exhaust piping.

 

http://wiki.answers.com/Q/What_are_t...ine_combustion

 

Those damn muffler bearings! lmao