in my case, I have only had the car a few months and not knowing how long the previous owner has had it cranked it up all the way, would turning it down some be the recomendation here? As mentioned I do not see heavy black exhaust upon heavy acceleration, in fact the only time I really saw anything significant was when an italian tuneup was performed. The car runs great. What are the signs that an IP has gone bad or is being affected? If any.