Last month on the C-10 we showed Classic Performance Products' trailing arm crossmember for the '67-72 Chevy trucks in preparation to run a new exhaust system through it-up out of harms way! The old exhaust system hung down too far after the truck was lowered and it didn't live too long as a result. I wasn't about to make the same mistake twice.
Obviously a heavily lowered C-10 with an LS engine and a 700-R4 isn't that standard in the world of pre-made exhaust kits, so one would have to be built from scratch. This is where Flowmaster's U-Fit Dual Kit comes into play. It is an affordable, comprehensive, universal exhaust system kit that you add mufflers and hangers to and cut and weld as your needs see fit (or have a shop easily do it for you). There are enough mandrel-bent tubes in the U-Fit Dual Kit to configure your exhaust just about anyway you want. It also includes pieces for a crossover or balance tube, as well as your choice of optional tailpipe exits.
Naturally, the Flowmaster...
Naturally, the Flowmaster U-Fit Dual Kit comes in a big box. Once you unpack it, lay it all out on the ground in some sort of symmetrical arrangement. To help visualize it fitting under your truck. The two smaller tubes to the left are for an H or crossover pipe and the flanges to go with it, should you so choose.
Of course Flowmaster has mufflers to suit just about anything and are known for their famous and aggressive 40 Series mufflers, but I wanted a muffler that was anything but "loud". My intent is to drive the C-10 on a daily basis and to do so with some sort of economy, which means I would have to keep my foot out of it and we all know aggressive mufflers aren't very good for exercising restraint. After expressing my needs to the folks at Flowmaster, they suggested their 50 Series SUV muffler. It is a larger version of the regular 50 Series muffler, which means it is quieter and thanks to a special tuning chamber, features reduced interior resonance. The Flowmaster website does a pretty good job of differentiating their mufflers as well and has all the physical dimensions of each muffler.
I decided to let someone else do the work for me this time and took the truck and the Flowmaster parts over to The Muffler Man in Placentia, California, for the install. Since The Muffler Man does this kind of stuff all day, every day, it only took about five hours for the install from start to finish. Going all the way out the back of the truck would take a little longer. We also didn't install a crossover tube in the system despite the advantages to using one because the exhaust runs through the trailing arm crossmember and it would make it impossible to remove the system without cutting it.
After some time in the driver seat I can say I'm quite happy with the results. The truck has a mild-mannered sound at idle and under normal cruising, but growls just enough to let you know it's there when the pedal goes to the metal. See more of what Flowmaster has to offer at www.flowmastermufflers.com.
 I personally didn't want to...  I personally didn't want to have too much exhaust noise or resonance, so after talking with the people at Flowmaster, they suggested their 50 Series SUV mufflers. These are much less aggressive sounding than Flowmaster's famous 40 Series mufflers. |  Here is the old exhaust system...  Here is the old exhaust system that was in the '72 with its X-pipe that ran under the transmission and over every speed bump and driveway in Southern California, basically destroying the exhaust after only a couple of years. This is the reason I wanted to use the Classic Performance Products' trailing arm crossmember with the holes in it to run the exhaust up in the chassis and out of harm's way. |  Due to the larger size of...  Due to the larger size of the 50 Series SUV mufflers, it was a bit of a squeeze to get them in the chassis. Their larger size will reduce noise and resonance to hopefully help me keep my foot out of the not-so-loud pedal. |
 Over at the Muffler Man in...  Over at the Muffler Man in Placentia, California, Josh has started with a head pipe coming off the header with a 90-degree bend in it that leads back to the inlet of the muffler. When it comes to exhaust work, you have to leave yourself plenty of leeway with the pipes until you are sure they will fit properly. See how he can't quite get the head pipe up over the trans crossmember until it is cut? |  With the head pipe cut back...  With the head pipe cut back about 6 inches, a piece of a bend is cut that starts to angle the tube upward and back to the muffler inlet. |  A corresponding piece of angled...  A corresponding piece of angled tube is marked and will be cut to hopefully join the muffler. Everything gets tack-welded together along the way once each piece (or pieces) fit. |