I have an 07 screw 6.5ft bed that has gibson bolt on catback system. On my old truck 07 ExCab 6.5ft bed had flowmaster catback system which I liked the sound of it better and I seemed to get better fuel economy out the old truck compared to the new truck the only difference between the 2 is the exhaust and the CAI old truck had the Airaid whistling wonder and the new truck has K&N polished tube. Do yall think that the Flows would have improved my fuel economy more so than the Gibson?

 

doubt it

 

Personally, I don't see how one performance muffler would give any better MPG over another. Now if the pipes are mandral bended on one set and not the other, then flow increases, and therefore you'd get some slight increases, but I doubt it would be anything that would sway your buying desicion.

 

There's going to be a natural variation in mileage between different trucks, even if they're outfitted the same.

Remember your Screw weighs more than your Scab did.

 

Thanks yall I didn't really think of the extra weight being factor maybe a lapse in judgment on my part...... Thanks again

 

It makes more difference than youd thing. my dad has a company issed extended cab and i have a screw and he gets about a half mpg better than i do...on highway....but he spends 90% of his time on gravel so he gets way worse overall mpgs than i.

another thing you might think about is did your previous truck have the 355 gearset and then you jumped up to the 373s? i made that jump and noticed about a mpg decrease in the 373s

 

You can not compare one vehicle to another like that. To many variables to consider before picking one thing to base a judgment off of. However, I feel that the Flowmasters would not help your fuel economy due to the minor restriction that a chambered muffler brings to the table. The best exhaust efficiency will only be achieved when the path of least resistance is obtained.

Personally I find is a little silly that chambered muffler manufactures even try to push their products as power adders. A straight through muffler holds the greatest potential for gains in both power/efficiency due to simply having nothing to restrict flow.

Before I ramble on much longer: I find it highly unlikely that any muffler would cause a noticeable differential in gas mileage.