Michael Johnson
Technical Editor
December 1, 1999

Step By Step

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Here’s an example of how not to do an exhaust system. The two rear catalytic converters are gone, the H-pipe is gone, the downstream air tube is closed off and welded to the exhaust, and the whole thing is just thrown together. As bad as it is, it might still be a bit better than stock, due to two less cats and the Flowmasters.
We start the removal process by loosening the exhaust from the headers. Notice the location and abrupt end to the downstream air tube. The air tube is one of the reasons people fell over laughing when walking under the car.
We loved the hanger for the passenger-side Flowmaster. Of course, before we got started we soaked all attaching points with a lubricant to help loosen all attaching hardware.
Removal of the old exhaust system wasn’t too difficult. The H-pipe was gone, so all we had to do was cut the pipe using a torch in front of the rear axle and remove the two pieces on each side.
Not only do the excellent JBA headers look much better than the factory stockers, they also flow much more air, thanks to larger 1-5/8-inch primary tubes. Much of the improved breathing comes from the JBA headers not being pinched at the flange like the factory stockers.
The driver-side header is easily accessed, but the passenger-side is another story. The air intake hose and all the emissions hoses must be removed from the air pump in order to gain access. Once these components are out of the way, remove the spark plug wires and remove the bolts that attach the factory headers.
Ah, much better. The JBA headers look great and they installed easily. The only problem was getting the rear-most bolt to go in because of the tightness of the header tube. Hold the header away from the head enough to start all the bolts, before tightening any of them down. Other than that, the headers were a piece of cake to install. Now we can go back and reinstall the plug wires, the emissions hoses, and the air intake hose.
Drive the car a day or so, then go back and retighten the header bolts, because after the first heat cycle the bolts might loosen, creating an exhaust leak. In some spots a 1/4 drive ratchet with a 7/16 deep-well socket can be used, but when it gets tight, use a small 7/16 open-end wrench.
The JBA headers include hardware that can be used to attach the H-pipe to the headers. We used a BBK off-road H-pipe that we had in the shop left over from a previous dyno test session. It was likewise easy to install. Without any catalytic converters to get in the way, an off-road pipe in any configuration is easy to install. Don’t forget to reinstall your O2 sensors.
This is a finished look at the off-road pipe. No rubs, no leaks, no converters, just the way we like them around here. And if cost is a consideration, an off-road pipe is much more affordable than a hi-flow catalytic H- or X-pipe.
Here’s a shot of the Flowmaster Force II system. It includes three-chamber mufflers and comes with all attaching hardware, except for a few small nuts and bolts we had to add. Our kit came with a 21/2-inch pipe diameter for extra breathing capabilities.
Loosely attach the flow tubes and mufflers to the H-pipe using a 9/16 open-end wrench combined with a deep-well 9/16 socket. Don’t tighten any part of the exhaust, except for the headers, until you’ve got everything lined up and fitting properly.
We used 7/16 nuts and bolts to attach the factory hangers to the mufflers. The old exhaust was void of any good parts, so here’s where we had to use new nuts and bolts not provided in the kit. If your car has a complete stock exhaust system, you won’t have to scrounge for bolts like we did.
Slide the tailpipes up and over the rear axle and connect them to the mufflers. Clamps are provided for you to use when attaching the tailpipes. Attach the clamps with the bolt heads up for a cleaner-looking installation, but remember, don’t tighten anything until you have everything looking good.
The tailpipes use the factory hanger at the rear. Major areas you need to check for clearance include over and around the rear axle, the upper control arms, and especially the gas tank area. Once everything checks out, tighten all the nuts and bolts and recheck your clearance areas.
What an improvement over what used to be here.
This is another area to be mindful of before tightening all the nuts and bolts. If the muffler is up against the framerail you will know it the second you start the car. In this case we had no clearance problems in this area.

If your Mustang is still breathing through the factory exhaust, you're missing out on improved sound quality and extra horsepower, especially if you're running a power adder. Even if your car has only simple bolt-ons, a free-flowing exhaust brings the fun factor up a lot, not to mention providing a good base for future mods.

The exhaust on Editor Kinnan's '87 LX made him the laughing stock of the Ford building here at EMAP Petersen. Even the art directors who don't drive Fords were taking pot shots at the thrown-together sections of tubing that made up Kinnan's exhaust system. [Ed. note: Hey, I didn't do it. I bought it that way!] However, the one thing the LX did have was a killer sound. That was mostly due to the Flowmasters that made their way into the crumpled exhaust system.

To remedy this situation, we got on the phone with JBA Headers and Flowmaster. The reason you don't see an H- or X-pipe manufacturer listed is because we planned on using the Tri-D Industries H-pipe left over from our H-pipe vs. X-pipe story in a previous story. However, the H-pipe and Flowmaster after-cat went together like oil and water. The convex mounting flange of the H-pipe was too big for the convex opening in the Flowmaster system--not by much, but enough that we would have had a big-time exhaust leak. In place of the catalytic H-pipe, we found a BBK off-road H-pipe which was languishing in the shop and decided to use it instead. The county Kinnan lives in does not inspect for emissions, so it was the perfect situation in which to use the off-road pipe.

The pipe that was on the car just about mimicked an off-road pipe anyway, so we forged ahead. Exhaust components make for a pretty straightforward installation, but set aside at least a day if you're doing it yourself.