Anytime I've put on new exhaust parts, they always smoke from the oil that they use on the pipes etc in manufacture. Hopefully that's what you are smelling
We just had dual exhaust put on our car yesterday. (we had holes in the exhaust pipes--would not pass inspection, so we had to get work done on the exhaust system anyway) I know what you mean about that smell . When we left the muffler guy, we went straight back to the place to have the inspection sticker put on--drove for about 5 miles--by the time we got there and everything had heated up, it smelled REALLY strong. A weird smell--not quite like gas. IDK--anyway, they said that the new pipes will sometimes smell that way initially. Hope so. Wish you the best--hope you can easily find out what is causing your to act up. I actually liked the way our car sounded BEFORE all the exhaust system work was done. Steve says it is glass-packs (whatever that is) with dual chrome exhaust pipes. Anyway--it sounded better when it was old rusty pipes fulla holes!