It's been a little while back but I installed a true dual setup with glasspacks, love the sound but low end torque isn't there. Since then I have gotten the Micro Chips tuner, this has added much better response but mostly in the mid to upper range.

My question is if I went to a different muffler would it help the backpressure and therefor the low end torque and if so will it aso affect the mid to high end??

Also since doing the tuner my mileage has suffered, was around 14.5 now averaging 12.5 and burning premium to boot. Will the added back pressure help hurt or make no difference to mileage??

Thanks, Doug

 

well you have a true dual setup, now the the question is do you have cat's on your truck? and are you running a H for X pipe on it also?

silver

 

What engine and what diameter pipes did you use?

 

Original cats still on, split at y and ran duals out the back, no x or H pipe, 5.4l FX4 package. Pipe is same as oe, I guess that would be 2 1/4

 

Nobody knows huh???

 

My stock diameter piping is 2.5, if that info helps any.

 

Just a quick question:

Do you have a picture of this in the gallery ?

I am guessing that there are 2 individual pipe runs to the back ??

Common old wives tale that Back pressure-TQ. Flow equals TQ.

If the xhst gas flow gets messed up due to the way the pipe was bent or routed, then this will reduce TQ.

The piep should have been 2.5" out of the stock Y pipe, which brings another question to mind, did the shop that did this use 2.5" the whole way, or switch to 2.25" or 3" ?

If you can grap a quick picture of the routing and stuff it in your gallery that might help with things.

The MagnaFlow cat back that is SI/DO with an exit under the rear bumper ( again complete pontification that is the routing ) has a requirement to remove the spare if memory serves me correctly. This is the only way MagnaFlow could get the system to flow test correctly.

Let us know about the complete pipe sizing that the shop did, and the pipe size that they used before and after the mufflers, and we might start to get some where.

Last question, what is the difference in TQ before and after the install, was it lost in the whole range or is there one dead spot, and if so at what RPM.

 

Pipe is same diameter all the way back, will try and slide my fat rear under there and take a pic.

It seemed to lose a little torque in the low end upon installation. I know from reading here that the general concensous is that the low back pressure will cause this, my question was that if I remove the glasspacks and replce them with magnaflows or like with a little more back pressure will it not only give me better torque but also will it affect my mileage?? And if so in what way better worse??

Thanks, FM

 

I jsut got true duals put on my truck today, and I also noticed alittle loss in power through the whole range. kinda sucks but at least it still goes, and sounds sweet to boot. I have 2.5 inch pipe and 18 inch glasspacks. no H or X pipe.

Putting a muffler on will make it quieter, but you probably will lose some gas milage since its not just straght through.Thats what I would think anyway, seems logical to me since glasspacks are mainly a straight thru design and mufflers have all that mumbo jumbo in them
I would think you should get some torqu back with a muffler too.

I stopped at Ford yesterday to ask a guy about my paint, and he had jsut got duals too, and said his gas milage sent up a mile or 2 per gallon.

 

That's odd. My experience is the opposite. My mileage increased after the MicroTuner.
From 12.5 before (was 13.5, but went to 285 tires which hurt the mileage)
To 15.8 after the tuning. (Although now with the winter fuel formulas, it has decreased to 14.7 on average)

Cutting off the factory muff and replacing it with 18 inch glasspack netted me 1 mpg, which is part of the 15.8 I mentioned. And it sounds way better without being too loud and keeps the low-end torque. I think it was about $25 at the local muff shop.

Truck perticulars below.

 

Ideally you should have had an x-pipe installed or use a Magnaflow X-muffler. You also should have used 2.25" diameter pipes instead of 2.5".

 

I have well not true because i left the cats on there but there as straight as it gets. Flowsmaster didn't sound right. Or maybe you should try one glasspack.

 

familyman...

I really believe RebelYell had the right idea (previous reply).

If had to do it all over again, I would stick with the stock piping, cut out the factory muffler and put in a Magnaflow or ProFlo and also replace the factory Y-pipe. Instead, I went with the Gibson 3" single and lost quite a bit of low-end torque and 1.5 mpg.

In your change-over, you went from a stock pipe outlet area of almost 20 square inches to a little over 39 square inches, double the area, which is the equivalent of a 3.5" single...very free-flowing, but inefficient from start to normal speeds. If you had a built gas-suckin' 426 cobra-jet and ran at the track all the time...your setup would work great.

On a side note...Mitch150 cut out his Gibson 3" muffler with a 3" ProFlo and he gained back some of the low-end loss he experienced after a single Gibson install.

Let us know what you finally decide to do.

Kevin

 

I also had true duals with no x-h pipe put on and had a similar problem with the torque and a loss of gas mileage. turns out it had to many bends in the pipes so i just cut the pipes off after the mufflers and put turndown tips ont it and now it runs great.

 

Only difference is I only lost mileage after putting the tuner in at the 91 performence setting.

I might try a muffler with a little backpressure but it'll have to wait, going to see Mickey Mouse and apparently he really likes money

After I return and build my reserve back I'll try something different.

On a side note, just changed the setting to 87 since the oil co's are sticking it to us around here, also cleaned my k&n even though the truck only has 17000 on it, seems to have made a difference but won't know for a fact till next fill up, just that this last 1/4 tank is lasting alot longer..... hmmmmm

FM