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kcmustang · 04-18-2005, 09:09 AM

Ok, first of all I have an 89 mustang LX 5.0L with an AOD tranny. I use it as a daily driver. I replace the whole exhaust system with Flowtech full length headers and Flowtech off road h-pipes. I have Flowmaster catback exhaust also. Now for my problem. I first install the catback exhaust. It ran fine and got better gas mileage. As soon as I put in the rest of the parts I went from 17mpg to 14mpg. What went wrong? I had the computer tested for errors and none came up. I think it is running too rich because it starts alot rougher almost as if it were carburated. It has never stalled though. I will say that it sounds great. I have many other aftermarket performance parts on it but they were installed way before my exhaust. What do u guys think?

04-18-2005, 09:09 AM	#1 (permalink)
kcmustang Junior Member Join Date: Apr 2005 Posts: 22	Ok I need some moderate help Ok, first of all I have an 89 mustang LX 5.0L with an AOD tranny. I use it as a daily driver. I replace the whole exhaust system with Flowtech full length headers and Flowtech off road h-pipes. I have Flowmaster catback exhaust also. Now for my problem. I first install the catback exhaust. It ran fine and got better gas mileage. As soon as I put in the rest of the parts I went from 17mpg to 14mpg. What went wrong? I had the computer tested for errors and none came up. I think it is running too rich because it starts alot rougher almost as if it were carburated. It has never stalled though. I will say that it sounds great. I have many other aftermarket performance parts on it but they were installed way before my exhaust. What do u guys think?