I have an 01 7.3 4x4

I ran a 4 in downpipe and 5 inch after that (4 is as big as you can go on the down pipe) and a 6in tip. It has no muffler and is nowhere near too loud. The turbo keeps it quiet. Farm Boy Diesel is the best company to order the kit from. The bends are good and shipped you are looking at like 350. A lot of companies resale this kit for close to double. I also built an air intake out of pieces from crashed psd's with intakes. Keep a lookout on ebay and you will find a good one for less than 200. If not just go with a k@n. The tony wildman 6 position tuner is the best but it takes a while to get it in and costs like 450. Stay away from Banks and Edge products unless you want to upgrade your transmission quickly. The zoodad is also a mod you will find out about on powerstroke.org. I cant reccoment Farm Boy Diesel enough though. I put a kit on a cummins and the one on mine and they are top of the line. The downpipe will look like it has a dent in it and it is for clearance. The hardest part is unclipping the downpipe off the turbo because of accumilated grime.

This is my first powerstroke too and I have done a lot of homework. Tony Wildman or Dp (Diesel performance) are the best tuners for the truck but it is a little complicated. You can link up with the site from powerstroke.org. GAUGES should be your first or second mod. Do not get a programmer with the built in ones as they arent very accurate. Do not get glowshift gauges as they read funny and are generally pos. I like the autometer. You need a boost gauge (something that goes over 25lbs) a pryometer (thie is exhaust gas temperature) and a transmission temperature gauge. Do not take your truck over 1250 on the perometer this is where your turbo will begin to melt stuff. You can run 1200 all day long and you could touch 1250 for a second or two but this should be considered your redline. Your transmission should never get hotter than 180ish. If it gets above that start looking for a rebuild kit. If and when your transmission goes you have to change the tranny cooler too because of the built up chunks in the lines. If you dont you will drasticaly shorten the life of the new or rebuilt one. It is still a good idea to have the tranny flushed every year (this is the trucks weakest link).When you change the fuel filter buy the one with the top plastic piece and not just the element. Do this every other oil change. All of these things leak a lil oil (im talking a drop or two every day or so) so dont let a little stain fool ya. They hold 14 quarts so you have a little room to drip. The foil delete and the zoodad are free mods that you should find out about. I did the foil delete and it sounds better. A good mod is also to switch intercoolers with the 6.0 truck. The 6.0 came with a 33% larger intercooler and this is a cheap alternative to buying a high dollar aftermarket one. You want lower exhaust gas temperatures and larger downpipes exhaust intercoolers and intakes get you there. I know this is a lot but these trucks are fun. If you want to know stuff about suspension lifts, 4x4 parts, and wheel and tire sizes send me a pm.