I'm looking for the optimum exhaust pipe diameter for a new system. I would like to get ceramic coated headers, retain the appropriate emmissions(cats) and redo the rest of the exhaust. I have an '01 F150 super cab 4x4 5.4L w/ a 3.55 LS rear end. The only mods so far are a K&N and a Diablo chip and a 70 series Flowmaster(I'll replace that when the headers go on). In the future I do anticipate an electric fan and maybe one or all of the following: Throttle body spacer(four hole), underdrive pulleys (with an overdrive alt pulley), ignition and MAF. Any and all future mods need to make the engine run more efficiently. The wife doesn't complain too much about adding stuff, if I can get better gas mileage, even incremental improvements. The vehicle is my daily driver and my get-me-to-the-playground truck on weekends. I don't tow anything nor do I really max out the carrying capacity (Although, I did break leaf springs on my last two trucks) and when I do load it up I usually drive slowly and carefully. I want the truck to sound good but perform better. I don't want it to be too loud in the cab. I realize that the loudness of the system is dependent on multiple factors. I've just spent hours reading exhaust forum posts and I'm still not clear as to what size diameter is best.
I'm thinking the best pipe diameter will be one that matches the diameter of the header. Is this right? I'm hoping for a system that shows improvement in the 1500-2500 rpm range without sacrificing too much performance when I get on it and wind that puppy out

I realize there are compromises. This is not a race car and is not being used as a real work truck, where all that torque is called upon often, so my choice would be to lose a little a the higher rpm's. I'm just researching this subject now with the intention of adding the headers next summer. Hopefully by then I'll have a better understanding of the subject matter and be able to buy the appropriate system based upon my actually usage/needs. I've called a couple of places to talk about the set-up and the responses sound very sales oriented, as one would expect.

Also is there a preferred routing of the pipe or is the stock configuration suitable? The current system exits after the rear passenger tire. I'm interested in the best possible layout and money is no object. Well really it is, but I want to start with the best and then make intelligent decisions as to where to cut corners if I need to.


Thanks,
Tim

 

i would go with 2.5" pipes

 

Thanks.