Whats the best way to check for exhaust leaks? I'm pretty sure I have a exhaust leak. just dont know where,

 

Visually.
Get under there and check for the leak. It should have a small amount of soot/carbon showing through the leak. At least, when mine springs a leak, that's how I track it. Either that or do it with the engine running and feel around (careful to not burn or affixiate yourself) for hot exhaust coming from anywhere but the end terminataion opening in your exhaust. If you got a buddy to help, he can put his hand over the exhaust pipe to limit the amount coming out and try to force it through the leak maybe making it easier to track if there isn't any soot/carbon showing yet.

Good luck!

 

Slopoke got it right, but you can also get yourself a bottle of soapy water and start spraying, you'll find it!

 

Found it. It was the exhaust manifold. Looks like the gasket is blown by the #4 cylinder. Is changing the gasket a easy fix. Any tips?
Thanks