yea ill get on that ill have it post asap hopefully by the end of the week

 

i have recieved nothing but very nice complements on the sound of it

 

The back pressure is maintained by the CATS and taking into consideration the leaning of the fuel mixture, the CPU can more than compensate for that. Sound is a personal preference, and depending on a variety of factors, in some situations (such as my present F150), you would never even know I have no mufflers.....I have even been asked if I'm running magnaflows! The flowmaster series (with the exception of the 2 chamber units) actually create greater flow restriction than the OEM unit.....check out muffler flow test in the net....also that parallels the dyno testing we did with our race cars back in the 90's.

 

The backpressure related to exhaust scavenging is unrealted to mufflers. It is generated in the manifolds/headers, primarily within the first 20 or so inches. If your running a stock manifold, there is barely a true scavenging (negative) pulse fed back to the port. This is why adding headers makes such a nice and noticable change in power. On a dyno you can realize 40hp at the rear wheels doing nothing but swapping from a cast ex manifold to a header. I have done this a couple times with 460 Ford engines and have seen the before and after results. By removing the muffler you do not change the pulse timing or length in the header or manifold. This is done with primary diameter, length, and collector design. A longer collector will yield you a longer/softer negative pulse, a shorter collector will result in a sharper/shorter negative pulse. There is a lot of science in thermaldynamics and a lot of research information on the net related to headers and why they have the effect that they do. It is not related to mufflers....other than a muffler adds to the overall resistance on the air's exit from the system and can end up being a restrictor of the engines ability to breath. A proper exhaust system with a muffler will hardly be measurable in power change between having the mufflers or not having them. To get to that point you need to have a muffler and pipe diameter that can allow the air fredom to escape without building up pressure. The backpressure your refering to for creating the negative pulse...or "the 5th cycle" of the 4 cycle engine is created in the initial run outside of the exhaust port. 4, 5 or 6 feet back is not relavent to this pulse timing or width.

 

I already cut off my muffler and fabricatd my own 3" Cat Back exhaust. It's the meanest sounding exhaust that i have heard yet on the F-150.

 

i got the clips for it however the clips are only from inside the cab on the road and on the highway as well two are standing behind it from start up how do i go about posting them

 

Ditto, replaced my muffler with a piece of pipe. It's not too loud & truck picked up some ET in the 1/4 mile, also gas mileage didn't drop. Got 14 towing race car & trailer on trip from Bay Area to Phoenix & back. My buddy liked the sound so much he did it to his '01 5.4.