When putting an exhaust system on my car/reducing the back pressure will i get better mpgs.?

Question

i wanted a glass-pack for my 97 Ford Crown Vic Police Int.

And if not could I change it from a dual to a single and then have the glass pack at the end?

Answer 1

about the only thing that will change is the sound....

Answer 2

The stock exhaust is capable of flowing enough to achieve maximum engine RPM. In every day driving you idle and use partial throttle so the stock exhaust is more than capable of handling the flow. Adding after market pipes is all about sound and how you feel about the car, will make no difference to your mileage.

Answer 3

Not going to make much, if any difference with a police interceptor.  It will help the engine breathe better, but there are some draw backs to that.  Any modification of the exhaust from factory stock CAN bring you a fix it ticket.  It doesn't mean it will, but it can, and if they can now hear you, your chances of being stopped have increased.   If you live in a state where inspections are a must, it can mess things up there.

The O² sensors need a certain amount of back pressure to give the right readings.  If they aren't getting it, it may trigger a check engine light, which is an automatic fail in those states that do checks.

Changing from a dual to a single would defeat the purpose, and you would have more restriction even with a glass pack.