Excessive steam.
 

Just put on a set of lightning headers. 2000 502 MPI. 145 hours. New impeller as well. I had a good bit of steam out of the starboard pipe with the stock manifolds but now it seems like I have even more. When I take off it really shoots a good bit out but as I run, it seems to stop. After I stop and idle, the steam comes up for a minute or two and dissipates.

Anything I should be worried about?

BTW, the headers gave me about 2 mph top end and quite a bit of mid range. I am just starting to bump the rev limiter so I need to work on the prop.

Probably nothing to worry about. I would double check to see if your water flow is equal on both sides. You can do the feel and touch routine or better yet an infrared heat gun to check temperatures. Look for any hot spots on your headers also. You should also do a spark plug reading to make sure you are not running lean. NO SHINY metal specks! You may need to run a adjustable fuel pressure regulator and bump it up a little. Don't want to melt it down now that it is staring to run better. :)