I have a 2000 Ranger (XLT, Ext Cab, 4x4, 3.0) and am thinking about installing a flow through exhaust from the cat back. For those of you that have done it, did you experience an increase or decrease in gas mileage?

 

It's all going to depend on the diameter of the pipe you use. On a 3.0, you're going to want something on the smaller side (probably less than 2"). The key to maintaining your power in any given RPM range is maintaining velocity. If you go too big, you will lose this, and it will hurt power. The common myth is that it's the loss of backpressure that hurts your low-mid range power, but it's got nothing to do with that. Oversized pipe allows turbulence that slows the scavaging effect to the cylinders.

 

true dat