Okay guys I need your help. I went in to get some Flowmaster 70 Series on the truck. When I went in I told the guy that I wanted dual in dual out. He then informed me that if I got that it would kill the gas mileage. He said with more air in the exhaust a sensor after the catalytic converter would sense a reduction in the exhaust temp, dump more fuel to increase the temperature, in effect giving me more horse power but cutting the gas mileage from 13.2 to like 8. He recommend that I get a single in dual out, but then informed me all that it would do, would be change the sound my truck makes, so just a cosmetic change.

Okay so here is my question if I get single in dual out what does that give me? Also is getting dual exhaust for a little better gas mileage and added horse power or have I been told incorrectly.

 

Sounds right but I am not sure 100% if you find out let us know that is a mod I will be doing in the very near future.

 

I have just had a single in and dual out magnaflow muffler on my 150. I havn't used a tank of fuel yet but I will keep you posted. I can tell you that it sounds very nice, a low deep tone, not loud and annoying.

 

Just installed a totally stainless system, Magnaflow, truck sounds great, not too loud. My son has flowmasters on a 2003 f150 screw 4x4 and his is a litle too loud for me, but he is 16, and louder is better for him. I have posted some pics of the install. Check em out

 

LSUFX4,

I have the Flowmaster series 70 dual in dual outs on my reg cab with the 4.6Ltr. I have noticed an average of 1.5 mpg since doing the upgrade at 2800 miles. I now have just under 6500 miles on my ride and I still get the 1.5 mpg increase over what I had before the upgrade. If the "dumping gas to maintain...." seems to be a problem then one could have their computer reprogrammed to reflect the differance in the exhaust temp. This is the 3rd vehicle I have installed the Flowmasters on and all 3 have given me small mpg gains with a good HP gain as well. My 94 3.4ltr Firebird has the 50 series and it is sporty loud and I have gained acceleration and mpg from the muffler and exhaust conversion. Just my 2 cents but I really like the sound and performance of my duals. Good luck.

 

more fuel and air equals more power which means that you dont have the engine reved up to what you normally do. Thus it should give better gas mileage since the engine isnt working as hard, meaning its working more efficent.

 

Oneagle1...
Did you just have them put on the dual in dual out with out changing the exhaust temp in the computer? And how much did you pay for install and parts?

 

wscott, I just looked at your gallery pics of the exhaust. Which magnaflow muffler did your purchase? I've looked at their cat back kits, but like your custom install alot better. Also, it looks like you took an different route from the muffler to the driver's side than some of the other "dual" installs. Please provide us with some more details.

 

I am not sure which magnaflow muffler that I have. I just went to a local cuatom muffler shop and they did the install. The only thing that I requested was that I did noy want the drivers side pipe to come out behind the rear axle. I have seen some kits where the pipes come out of the muffler and go over the rear axle, drop down and go over to the drivers side. the problem with that application is that the cross over pipe is visible from behind the truck. The guys at this shop are very good and they have done my work for years. I am sure any shop can do the cross over llike this. I will try to find out what magnaflow muffler that I have and let you know. truck sounds awesome, not too loud but still a deep sound. My neighbor bought the borla system and he hates the cross over pipe. He is going to the shop monday to get it changed over.

 

WSCOTT

I also have the magnaflow exhaust. I was wondering if you noticed a change in fuel economy since the change? I noticed I dropped 2 mpg on the first tank after the change but I think it might be from a heavy foot, while listening to the smooth sound, if ya know what I mean!

 

LSUFX4,

I had the system installed from the cats back. The exhaust shop did their own mandrel bending of the pipes. All parts and labor with tax was $285.00. No I did not have the exhaust temp changed in the computer. I have not experienced any problems since the install.

 

DFK150
I have not noticed a change in my fuel economy since the magnaflow install. Although I think I have had my foot in it a little too much to hear the exhaust. I'll keep you posted as soon as I get used to it and start driving normal again.

 

Oneagle1Just wanted to clarify if you had any change in fuel economy for better or worse?

 

wscott,

Thanks for the info looking forward to hear your results.