does it make a difference on an DTM exhaust from magnaflow...i got some cheap ass one already installed and it seems like my car is backing up with exhaust fumes...and my bumper has black smoke stained on it...wat does that mean about my exhaust?

 

means ur car is burning rich. nothing to do with the muffler. u got a 2.x or 3.0?

 

it can also mean that when u installed the exhaust, you didn't have it far out enough and so the smoke gets onto the rear bumper. thas wut happend to my accord.