A few years ago, we did a six-cylinder to V-8 swap in a '67 Mustang hardtop. For the most part, the conversion has been successful, making the car more fun to drive. Because we went with a five-speed and 3.55:1 gears, it's snappy and more fuel-efficient. The six to eight conversion hasn't been without its headaches; we've had to work out one bug at a time, like a leaky carburetor and improper ride height.
Another problem has been a loud exhaust system. Although the throaty 21/2-inch mufflers sounded terrific, they were louder than the owner prefers. So we called Scott Halseth at National Parts Depot to see what he had available for our Mustang that would keep its throaty demeanor without being too overbearing. He suggested one of NPD's new aluminized, original-style 21/4-inch dual exhaust systems with turbo mufflers and 289 High Performance exhaust manifolds. You can get into a complete system for under $500 depending on the system. Hi-Po manifolds are another $274.95 plus tax and shipping. See NPD's online catalog at www.npdlink.com.
Mustangs Etc. in Van Nuys, California, moved the previous exhaust system to a '70 Mustang, then installed the NPD dual exhaust.
The NPD aluminized dual exhaust...
The NPD aluminized dual exhaust system arrives complete with hangers and hardware. You may have to custom tailor your order depending on how you wish to hang the system.
The 289 High Performance exhaust...
The 289 High Performance exhaust manifolds from National Parts Depot are the best specimens we've ever seen, with nice castings void of the usual flaws. By the way, that's Garrett Marks of Mustangs Etc. If he can't find the part you want for your classic Mustang, it can't be found.
With the existing dual exhaust...
With the existing dual exhaust system removed, the first step is installation of the 289 High Performance exhaust manifolds and H-pipe. Occasionally, you will find the H-pipe doesn't line up perfectly with exhaust manifolds. It can be hand bent for proper alignment.
NPD provides the exhaust donut...
NPD provides the exhaust donut gaskets, which seal the union between the manifolds and exhaust system.....
....Retaining nuts should...
....Retaining nuts should be uniformly torqued until the union is tight without distorting the gasket.
Exhaust pipes follow the floorpan's...
Exhaust pipes follow the floorpan's contour so they cannot be seen if the car is viewed from the side. National Parts Depot went to great pains to ensure identical routing to your Mustang's factory exhaust system. Where this system does differ from factory ('67-'69) is dual mufflers instead of a single transverse muffler, which you can also order from NPD. This is a true dual exhaust system, which follows what Ford did on '65-'66 Mustangs and switched back to in '70.
The exhaust pipes are seated...
The exhaust pipes are seated in the H-pipe like this, using a 2x4 block for protection. Make sure the pipes are exactly where you want them before doing this. Once they're seated, they're impossible to turn.
Installed exhaust pipes should...
Installed exhaust pipes should look like this, routed close to the driveshaft and tunnel-again, where they cannot be seen in a side profile.
Mufflers are positioned and...
Mufflers are positioned and checked for proper fit. Fit is excellent.
Because our '67 Mustang already...
Because our '67 Mustang already had exhaust hangers, we elected to go this route with pipe hangers instead of the welded on muffler brackets.....
....Where the NPD system differs...
....Where the NPD system differs from some systems is center in and offset out like a '65-'66 Mustang dual exhaust system.
Tailpipes can be challenging...
Tailpipes can be challenging in any situation and these are no exception.
Your goal with the tailpipes...
Your goal with the tailpipes should be getting the risers clear of the rear axle while achieving proper alignment at the valance and tailpipe mounts.
As with the H-pipe, the mufflers...
As with the H-pipe, the mufflers and exhaust pipes mandate a little tweaking. This happens because when pipes are formed and welded in fixtures, they cool and change shape. Expect this with any exhaust system.
These tailpipe tips are roughed...
These tailpipe tips are roughed in, but need to be cut shorter with turndowns so they cannot be seen. They can also be fitted with accessory tips.
Where possible, turn the exhaust...
Where possible, turn the exhaust pipe clamps so they're out of the undercarriage slipstream. In this case, they need to be turned up so the studs cannot be seen.
The NPD dual exhaust system...
The NPD dual exhaust system offers a nice, clean installation with adequate clearance all around.
Your NPD tailpipes should...
Your NPD tailpipes should look like this-routed smoothly above the rear axle so they clear everything, including rear axle vent and brake hoses. Looks like this Mustang could use a new vent hose.