Straight pipes and mpg

Bull hauler that is because you have less restriction and back pressure on the exhaust system.

 

I can not stand the sound of straight pipes when i want to sleep, but 7/10 of a mpg........ id like to see how your numbers look long term. not to mention some places will bust your balls over straight pipes. my pittsburg power exhaust is loud enough.

 

I picked up .5 mpg switching to free flow mufflers, so if he had really restrictive mufflers, he could very easily pick up that much.

 

If you do an oil analysis, your oil will be cleaner on the second oil change.

 

Mufflers??? What's that?

 

They have been trying to pass a law in the FMCSA that outlaw straight pipes without some type of noise suppressor. The old law stated that a turbo was a noise reducing device (I believe it was in 1976) and they want to get the law more up to date. I think it failed twice. But they keep trying. Here is a link to where they tried.. http://www.fmcsa.dot.gov/rules-regulations/administration/rulemakings/final/Noise-Emission-Standards.aspx


And the actual rule..
325.91 Exhaust systems. A motor vehicle does not conform to the visual exhaust system inspection requirements, 40 CFR 202.22, of the Interstate Motor Carrier Noise Emission Standards, if inspection of the exhaust system of the motor vehicle discloses that the system—(a) Has a defect which adversely affects sound reduction, such as exhaust gas leaks or alteration or deterioration of muffler elements, (small traces of soot on flexible exhaust pipe sections shall not constitute a violation of this subpart);(b)Is not equipped with either a muffler or other noise dissipative device, such as a turbocharger (supercharger driven by exhaust gases); or(c) Is equipped with a cut-out, by-pass, or similar device, unless such device is designed as an exhaust gas driven cargo unloading system

 

try shutting truck off when you go to sleep, would also help your mpg... as far as busting your balls in some areas for straight pipes, cat's are not all that loud as long as you are reasonable with the peddle so take her easy going through small towns and scales and you will be just fine