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Old 05-23-2008, 01:12 PM   #6 (permalink)
EcoModding Lurker
Join Date: May 2008
Location: America
Posts: 5

The GT - '86 Pontiac Fiero GT
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Originally Posted by DifferentPointofView View Post

How do you know it increased your mileage if you never tracked it? Did you just take what the exhaust companies claimed and added it together? Just to say, but a free-er flowing exhaust doesn't necessarily mean more mpg's. It really depends on what rpm range you spend at most.
Well I know that my mileage increased for a fact because my old catalytic converter was almost completely clogged up and I could not rev the engine about 2.5 - 3 grand haha. I was having to get gas almost every two days. That said I replaced the exhaust and cat at the same time and attribute all gains to the cat not the exhaust. As for the headers, the stock ones are really inefficient and have a protruding piece of metal inside of them. I am also on a fiero forum and I based my claim of an estimated "2-4mpg" off of what one fellow fiero owner measured after installing the same headers. My mpg increase was probably more than that because the stock headers were cracked causing the O2 sensor to think the car was running lean and compensated by dumping more fuel into the engine. It was apparent that I gained some mpg just by fixing those problems so I can guess that I have 2-3mpg better than stock, assuming that my engine is in good repair. Your right, I will know for sure when I start a log.

here are some pics of my car

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