I want to increase my gas mileage and know that a true dual exhaust would do this, but cannot find anyone who makes them. Do I need to have them custom made? Thanks in advance for all help provided.

 

A true dual exhaust will not increase mileage all by itself, it must be sized correctly and designed correctly. Too large a pipe will over scavenge the cylinders during overlap when both intake and exhaust valves are open causing a loss in both power and mileage. To small will not scavenge all the exhaust out of the cylinder, diluting the incoming fuel air mixture with exhaust gases. Likewise a properly designed single exhaust can out perform duals for the same reasons. You did not say what engine you have but this is more critical on a gasser than a diesel.

 

All a true dual exhaust will do is make more noise. Back pressure at road load is pretty low, since the factory system is sized for WOT airflow.

 

My engine is a V-10 6.8 My thoughts on a true dual are this, and engine is just an air pump, so the more air you can get in and the more you can get out, makes it more efficient. I have a 1990 Mustang with dual exhaust and a cold air intake and get 17 MPG around town and 22 on the road. Would this not work for my truck?

 

If you're not going to install true equal length headers first, you are wasting your time, and by default, your money. You will gain no benefits at all with dual exhaust with the stock exhaust manifolds, unless you already have damage or blockage in your existing exhaust.

Most "street" headers you buy are also not true equal length headers btw.

Best way to improve your mileage, assuming your truck is in good running tune, is to just slow down, and moderate your right foot while driving.

 

My way of thinking is that the mfg's have been in the hp, tq, I can pull more than they can wars long enough to put about the best you do on their trucks and still be legal. There is a guy that lives down the street with a open piped cummins that can't leave his house without it wide open. I keep the shot gun in the attic and the shells in the basement to give myself time to think.

 

With the v-10 you didn't say which year but if it's an earlier one 04 or older you should do spd y-pipe and leave the exhaust quite. If you think that Cummins is loud and sounds like crap wait till you hear your v-10 they sound terrible. If your going to do anything there are a few bolt on kits which are all I think pretty much all single exhausts that exit in the factory location and if there are duals they are going to be a single in dual out muffler then just have 2 tailpipes Most of those bolt on kits aren't too loud but your not really going to gain anything but sound anyway and again they don't sound good to start with the biggest gain for exhaust without doing headers is the y-pipe.

 

I didn't see any noticeable mpg increase with the long tube headers, higher flow cat and catback exhaust (all mandrel bent) on my V10. More power but gas mileage is essentially the same as stock.