Build Your Own Exhaust at Home

Like it or not, thanks to The Man's lack of humor regarding openheaders, you need to run some sort of exhaust system on the street andeven at some tracks. Not so long ago, choices for performance exhaustsystems were limited to either stock pipes spliced for headers and maybeturbo mufflers, or a trip to the local muffler shop for some custom-bentduals. Either way, you got relatively small-diameter pipes that wereformed with a conventional bender, leaving crimped curves that furtherreduced the pipe's effective cross section. Flow suffered as a result,making a full exhaust system a real compromise for high-powered streetmachines. Alternatives, like running big, straight pipes, mufflers, andturndowns ahead of the axle, can help keep power up but tend to makeroad driving a chore thanks to thundering noise and ground-clearanceissues.

When this Camaro's exhaust system was built back in the '80s, we werehappy just to find replacement factory-style pipes so a tight-fittingdual system could be made with aftermarket mufflers. It worked for yearsbut had to be costing power with its 21/4-inch crush-bent pipes andancient crossflow muffler. Now we can install a 21/2-inch mandrel-bentFlowmaster system that should fit just as well but will flow and soundbetter. We can do it ourselves with relatively basic tools.

Obviously, larger tubes flow better, but eliminating the crimped bendsof stock-type pipes is probably an equally significant improvement.Before mandrel-bent pipes were offered in kit form, using them in anexhaust system meant fabbing the pipes by cutting and welding universalmandrel bends to straight pipe. Buying a kit requires a lot less skill,which we like.

The stock system on most early F-cars uses a transverse muffler hungbehind the axle. This isn't an ideal flow arrangement, though it doesprovide an advantage in ground clearance. Flowmaster offers several kitsfor early F-cars, but its transverse version uses a single muffler casein the stock location that contains two separate mufflers, and theinlets enter the case through the top rather than the ends as withstock. It should flow more without taking up more space.

We're luckier today. Exhaust solutions we could only dream about can nowbe obtained with a simple phone call or mouse click. Big-tube exhaustkits using mandrel bends to maintain consistent diameters minimize powerloss and are readily available from a variety of sources, for numerousapplications, with plenty of muffler options. As a bonus, you canprobably handle the installation yourself.

1. Step one was removing our old system, some of which had been in placefor over 20 years. Stubborn rusty slip joints are almost a guaranteedcut-off item, but if you plan to retain the exhaust manifolds as we did(see Save the Manifolds sidebar) you'll still have to get the pipes off.Fortunately, we installed brass manifold nuts on the driver side in1986, and they loosened right up. The steel nuts on the passenger sidewere more troublesome, and we considered ourselves lucky that only onestud broke. Penetrating oil should be applied liberally well before thedisassembly attempt.

2. Exhaust installers often recommend starting at the rear and workingforward, since most of the fitment issues lie with muffler placement andover-the-axle tubes, but we started at the front to make sure the kit'spre-welded H-pipe is compatible with our manifold setup. We didn't clampanything until we were sure everything was in the right spot and trimmedto the right length. We slipped the pipes together and hung them fromthe car with bungee cords and small lengths of rope. This also helpedset the height of the pipes relative to the floorpan, crossmembers, anddriveshaft. The front pipes are actually separate from the H at theangled section (arrows), providing some adjustability, and seemed toline up with the Pypes downpipes easily.

3. This particular kit is actually intended for first- andsecond-generation F-cars, so some of the tubes will need to be trimmedfor proper fit on the smaller first-gen car we're dealing with. Theinstructions advise where to expect potential fitment problems and givedimensions for cuts, but sizing up the stuff for yourself is the bestbet. The first potential problem area we found was the union between theH-pipe and the tubes leading to the muffler. Since the placement of themuffler is dictated by the available undercarriage space, we marked thetrouble area but waited to make any cuts until after trial-fitting themuffler.

We decided to tackle the exhaust upgrade on our '69 Camaro to replacethe stock-style duals that had seen better days. Using components fromPypes and Flowmaster, we were able to get the entire job done in the CCshop without doing any welding, though we'll probably go back and lay afew beads to add durability and positive sealing at the joints thatwon't need to come apart again. We also investigated a few optionalitems that may be helpful on your system. Oh, and for those of you whodon't drive bellybutton cars, we've checked out some universal optionsas well.

4. Here's where the old "measure twice, cut once" deal comes into play.Our H-pipe was temporarily hung and the muffler was positioned with ajackstand. The clearance of the case, curve of the inlet pipes, andposition of the tailpipe outlets make its proper location fairlyobvious. Next, the pipes that connect the muffler to the H-pipe weretest-fit, revealing that the H must move toward the engine by shorteningthe head pipes leading to the Pypes downtubes. We held off on makingthose cuts until everything had been trial-fit.

5. Areas that needed immediate trimming were the tubes leading into themuffler--the instructions say they have to be shortened by 21/4 inchesfor first-gen applications. Cutting the tubes could be done with ahacksaw, but that'll wear you out fast, especially with the thick-wallstuff Flowmaster uses. Our favorite, the Sawzall, makes quick work ofpipes, but making perfectly square cuts can be tricky. Instead, we useda chop saw for accuracy. This one, made by Clarke and available fromEastwood, was reasonably priced and made accurate cuts in mere seconds.

6. Although most of the slip-fit joints were willing to stay togetherwithout clamps for the trial-fit process thanks to their horizontalorientation, a few needed help. Rather than risk crimping a new pipe byovertightening a U-clamp, we used a couple of band clamps for temporaryfitment. Band clamps are intended as a permanent solution to slip jointsthat need to remain removable, and they are effective, but most of ourjunctions will be welded when finished.

Save the Manifolds

Although most performance exhaust systems willincorporate headers, we're going to stick with manifolds for a while. Inour case, the mechanical clutch linkage and the air-conditioningevaporator coil housing conflicted with some tube-header designs, and wehad some future improvements in store and wanted to hold off on headersto avoid other clearance issues later on. Other guys might just want tokeep the stock look under the hood. There are also those engines thatcame with headerlike cast-iron manifolds. The trouble with retainingmanifolds has been that most modern exhaust system kits are intended forheaders and begin under the toe board where a header collector wouldlie. Most factory manifolds are intended for a 21/4-inch pipe, soconnecting them to a 21/2-inch system requires some sort of step-down,typically necessitating a muffler shop, and it often ends up lookingugly. We recently discovered a bolt-on solution from Pypes PerformanceExhaust. Pypes is relatively new to the aftermarket performance exhaustscene, but one of its unique offerings is a line of manifold downpipesdesigned for factory musclecar applications. The downpipes combine astock flange with a mandrel-bent 21/2-inch elbow to mate with abig-diameter aftermarket system. Pypes also offers its own line ofcomplete exhaust kits, mufflers, X-pipes, and other performance exhaustparts and accessories, all aimed at the musclecar market.

7. Early F-body tailpipes are somewhat unusual in that they come out ofthe side of the muffler and have to snake their way between the tire andthe frame as well as around the leaf springs to make it out the back.The stock pipes were snug and only 2 inches in diameter, so properplacement of the 21/2-inch Flowmaster tubes was absolutely critical.Remember that a little wiggle room will be needed so the pipes canvibrate without causing rattles. In this particular application, therear wheels and tires also needed to be test-fit before final assembly.

8. Once the system's placement was finalized, the hangers wereinstalled. Since the Flowmaster system is dimensionally different thanstock, and probably a bit heavier, the kit includes unique heavy-dutyhangers. The forward hangers (shown) mount to the floorpan and requiredremoving the back seat for hardware installation, while the tailpipehangers come with self-tapping bolts.

9. The tailpipes on this kit are unfinished, again because the kit isused for two body styles. We could mark the pipes, remove them, and thenuse the chop saw to trim them back or cut a slash in the end, but we'regoing to accessorize using some Flowmaster stainless tips. SomeFlowmaster kits include stainless tips, and we prefer that look tochrome for this car. Check the Flowmaster catalog (also on its Web site)for other options.

10. Another accessory item we wanted to incorporate is the ball flange,which is also available from Flowmaster. Ball flanges offer a durablejunction without requiring gaskets, so they can be disassembled andreassembled repeatedly without issue. Our idea is to install the ballflanges at the back of the H-pipe so the center portion of the exhaustcan be dropped to make driveline maintenance easier. The inspirationcame from the stock setup used on 5.0-liter Mustangs.

Although the transverse-muffler arrangement of this system offerssuperior ground clearance, it's not the quietest system Flowmasteroffers. If this becomes an issue, we may install a pair of Flowmaster'snew Hushpower resonators. Designed to be used with Flowmaster mufflers,these resonators are intended to be mounted aft of the mufflers. Thatwould be impossible on this application, but there's plenty of room inthe conventional muffler position. The Hushpower cases are low-profile,so ground clearance shouldn't suffer. We'll wait to try the systemwithout them first.

So what if your car isn't covered by a specific kit? Flowmasteraddresses nonspecific exhaust needs with the U-Fit Dual kit, offered in21/2- and 3-inch versions. The kit includes tubes to create a completedual exhaust with crossover tube and tailpipes, including enough bendsto accommodate varying undercarriage arrangements. Mufflers are soldseparately. We'll be using this 21/2-inch kit on the CC/Rambler in thenear future.