smoke question?

i have a 93 civic and it has been sitting for approx. 2 years and i just got it ready to ride and it is smoking a little bit which concerns me!! i put some aftermarket headers on it and the chrome is rusting and i wasnt sure if its from that or bacause the headers are warped or something? i put new gaskets on when i did it but it looks like its smoking where the headers meet the downpipe not on the engine. it also has a bad o2 sensor!! any answers please? thanks!!

possibly collected crap there that is just burning up.

old gas mayb. drain the gas in ther and put in some new and mayb that ill take care of it