No matter how it happens, in every exhaust system, gases need to be carried from the engine safely rearward so that none of those fumes get into the passenger compartment. There are more ways to do this than we magazine types have ways to fancily describe when mentioning exhaust systems in a truck feature, but it doesn't really matter how--just as long as it happens, right?
Sure, some people might get away with running nothing but open headers, simple dump tubes, or any combo of both, but not around here, and not for very long. Of course taking your truck to the local muffler shop to have a few sticks of galvanized tubing bent up is a feasible option for most people and certainly does the job. The problem with this is the life expectancy of a mild steel exhaust system and the typical pinched bends in the tubes done with a non-mandrel pipe bender. There is only one way around both of these issues if you are building a truck that warrants it--build a custom exhaust system with mandrel-bent 180-, 90-, and 45-degree bends. When done right, a mild steel or stainless steel exhaust built using mandrel bends can look like seamless tubes snaking through the framework of any truck. If you are going to put this much work into it, you might as well use stainless so it won't rust out.
I located Stainless Works online, and looking through their website I found all the stuff I needed to build a top-notch exhaust system for my '68 F-100. After deciding that I'd use 2-inch tubes, I had a choice of either their butt-weld or slip-fit basic Rod Builder Kit. I chose the former. First timers might like the slip-fit option, except if you have to make a cut in the middle of a bend, you might lose certain slip-fit joints and will still have some butt joints to deal with. In my opinion, a butt-weld system might actually be easier to deal with, as long as the chop saw you are using is set up to cut as close to exactly square as possible.
To round out the rest of the exhaust system from Stainless Works, I picked two of their straight-through turbo mufflers with the inlet/outlet configuration I thought I'd need; three-bolt flanges so I could make the mufflers totally removable; their trick exhaust hanger brackets; and some polished bell tips. Stainless Works makes over a dozen different polished tips to put the finishing touches to any exhaust system, even the one that may already be in your truck. I put quite a bit of thought in how I wanted the exhaust to exit the truck, both the tip style and its location. This can make or break all the hard work done under the truck that almost nobody will see when it's on the road, so it does deserve some good eye-ballin'!
Like most other fabrication projects, cleanliness is the key to quality results, especially when a TIG welder is involved. Even though a MIG could be used with thin stainless wire, both sides of mandrel bent tubes are always greasy and/or oily since they need lubrication to make such smooth bends. Liberal use of rags and brake cleaner will do the trick once some cuts are made. I started TIG welding my tubes with typical 1/16-inch ER308 stainless filler rod, but it proved to be too thick for the little to no gaps I had in the butt joints. I went to the local welding supply store and got a pound of 0.045-inch stainless, which worked better.
 Here are all the parts from...  Here are all the parts from Stainless Works I'll be using to build the exhaust system for the '68 F-100. Their 2-inch butt-weld Rod Builder Kit contains all the general pieces of tubing needed in the form of four 48-inch straights, four 180-degree U-bends, four 90-degree elbows, and four 45-degree bends. I picked the inlet and outlet location on their straight-through turbo mufflers and added enough hangers and flanges to connect to the headers. |  These are the '05-'07 Shorty...  These are the '05-'07 Shorty Mustang headers I got from Ford Racing Performance Parts with the 4.6L three-valve engine. They come with new gaskets and hardware and are a replacement header for the stock cast exhaust manifolds. They'll be coated when it's all said and done. |  A more common practice in...  A more common practice in modern-day exhaust manifolds is this male and female ball socket connection. This is supposed to seal easier than conventional flanges. I had to slip my engine-side flanges on a piece of the straight tubing and take it to a local performance exhaust shop so they could "bell out" the ends to fit the headers. |
 I cut the straight piece with...  I cut the straight piece with the belled ends in half and bolted each piece to each header; these head pipes are pointing toward the ground here. Using masking tape and another straight piece of tubing, I mocked up where I wanted the exhaust to run under the truck. To join the two, I grabbed a U-bend and eyeballed where it might need to be cut while keeping it lined up with the head pipe. |  The chop saw is going to be...  The chop saw is going to be your best friend and will cut stainless steel the best; just make sure to cut square. After cutting, always chamfer and clean up the cut edge with the saw blade edge. Flat, clean cuts are going to pay off in the long run. Cut long, too--it's easy to cut more if you need to, but you can always weld pieces back on if you end up short. |  Not only does the head pipe...  Not only does the head pipe need to come down and back, it also needs to move toward the center of the truck too. With the U-bend cut, I can get a better idea how much needs to be cut off the other half. |