Bought a preowned 2013 St less than 10,000 miles on it and it looked every bit of it. I mean there was factory plastic still on things. Previous owner put a catback magnaflow exhaust 2.5" pipes and a green filter. The dealer removed the green filter and replaced it with a generic OEM filter. I'll get into the reasons why he did this but I will say swapping the green filter back to factory did not fix the issue. I would like to know since the exhaust was upgraded how essential is a high performance filter such as the green filter going to compliment the exhaust?