It's your fuel map,that's why your unloading in 3rd(itold you it was 3rd)I'll adjust you fuel trims and tune your NOS down an you'll run 9's.

 

just deal with it. all cars put out black soot to a certain extent. when you get the ottp tune it will stay the same or get a little worse because ottp tunes run rich (dumping more fuel) so where ever you live your motor wont blow.
the reason why you didn't notice before is because the stock muffler outlet is a lot smaller than the megan exhaust.

so wrong...

 

i expect black soot coming outta my 400 big block in my '78 bronco or outta my 350sb, not so much in a car with 37k miles on it.

 

it can happen to any car 4cyl to v12
ff to 30sec
if you look close you can see my car running rich as hell lol but i have a black car hehehehe
YouTube - Cobalt SS open down pipe

 

You just need to get it tuned. You see it all the time on these Imports that are chipped up. It's not the exhaust. My Civic did it too after I put a turbo on it. I had it untuned and loads of black smoke came out the back. Just try and keep it clean until you get it tuned.

 

well thx for the help and ideas.