I have a 2007 Mustang GT with Mac LT headers 1 3/4 and o/r x pipe and Borla exhaust JLT intake Sctx3 91 tune i get 16 miles per gallon which is scary already im not sure why is my mpg low but i want to put cams will this make my mpg worse than it is and please let me know why my car is wasting to much gas with the system i have already thanks