OK, I'll bite. So... an x pipe will sound deeper, offer a more efficient exhaust... maybe slightly better torque and is inexpensive to accomplish? Sounds like a no brainer! ...but I have also noticed that no one has mentioned the effect on fuel consumption...

I put a flowmaster on my GMC Yukon and absolutely loved the improvement to the sound of the vehicle, but the fuel economy went into the toilet. Before I was getting 17-19mpg... after the flowmaster and K&N install it went to 12-15mpg.... no noticable power or torque increases, but sounded mean and not too obnoxious.... I'm wondering if the x-pipe conversion on my 4.6is would have the same effect?


...what's the real impact on fuel consumption (before vs. after an x-pipe)?

__________________