John Hedenberg
September 1, 2003

Step By Step

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0309mm_01z Ford_Focus_ZX5 Front_Side_Track
Our Infra-Red Clearcoat '02 ZX5 has recently dipped into the 14-second zone with the addition of a Nitrous Express 75 hp wet nitrous system. Although impressive, our exhaust tone was anything but. We rectified the problem with a Focus Central shorty header and a 2 1/4-inch Magna Flow cat-back exhaust system. Did we gain any useable power, you ask? You'll have to read on to find out.
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The Focus Central shorty header (right) is noticeably larger from stock and coated, reducing under-hood temperatures considerably. This particular header connects to the factory catalytic converter with no modifications whatsoever and has 1-5/8-inch tubes. Focus Central also makes a long-tube design that takes the place of the converter for off-road, racing applications.
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For the exhaust system we went to the pros at Magna Flow in Rancho Santa Margarita, California. Its '00-03 Focus exhaust kit fits the ZX3 and ZX5 and is made from a mandrel bent, stainless steel construction. The pipe diameter measures 2 1/4-inch (stock is around two-inches) and eliminates the resonator at the rear of the system, adding to the overall flow and creating a crisper sound. The mirror-polished muffler works with a 3 1/2-inch, double-walled polished tip.
0309mm_03z Ford_Focus_ZX5 Underhood_Exhaust_Heat_Shield
After removing the OEM heat shield, our factory header is in plain view. It is a superior design when compared to a cast exhaust manifold but far from ideal in terms of performance.
0309mm_04z Ford_Focus_ZX5 Underhood_Factory_Header
The stock header can be removed in about 30 minutes and connects to the head with nine 10mm bolts.
0309mm_05z Ford_Focus_ZX5 Undercar_Catalytic_Converter_Flange
The catalytic converter attaches to the bottom portion of the header with three 15mm bolts. In order to gain enough access to wiggle it out, you will have to loosen the two bolts attaching the converter to the frame at the bottom of the vehicle. This will enable you to lower the converter enough so the three 15mm studs will clear the header. Otherwise, it will never come out. Note the oxygen sensor to the left.
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With the converter and pipe assembly lowered from its original resting place, the header can be removed from the engine.
0309mm_07z Ford_Focus_ZX5 Underhood_Close_Exhaust_Ports
Note the shape of the exhaust ports. There looks to be quite a bit of room for porting, and in the future, we might even give it a try.
0309mm_09z Ford_Focus_ZX5 Underhood_Focus_Central_Header
With a new gasket in place, we wrestled the Focus Central header in place and tightened the nine flange bolts down. You must have patience when tightening down the bolts, as some of the bolts are hard to access because of larger tubes on the header.
0309mm_10z Ford_Focus_ZX5 Underhood_Focus_Central_Header_Flange
In time, though, you will be able to tighten them. We used a combination of wrenches, sockets and elbow grease to accomplish the feat. The Focus Central header does not use the OEM heat shield.

When we last left you, our '02 Focus staff car, The Red Hot Chili Pepper, was living the good life. With a small 75 hp shot of juice from Nitrous Express, we dipped into the unthinkable 14-second zone in the quarter-mile. The only other mods were a Steeda cold-air kit and a 65mm Focus Central throttle body--not bad, right?

In this trim but off the bottle, the Pepper turned the Crazy Horse Racing chassis dyno to exactly 100 front wheel horsepower and 105 lbs-ft of torque.

After all the fun we had with the jug, we began to brainstorm about what could be done to improve the power potential even more. We wanted to keep it simple and, after some careful planning we decided to toss the weak exhaust system for a more improved and free-flowing design. This should improve our overall tone and maybe even add a few ponies, or so the thinking went.

This would include tossing the inadequate two-inch factory exhaust setup for a stainless steel 2 1/4-inch version from Magna Flow in Rancho Santa Margarita, California. We'd then scrap the somewhat restrictive header for a 1 5/8-inch shorty header from Focus Central in Tehachapi, California. We hoped to get one of FC's high-flow cat setups but they weren't in stock at the time of our install.

"Our shorty header will add approximately one to two horsepower to a stock engine," explained Dennis Hilliard, owner of Focus Central. "On your car, with our 65mm throttle body and your Steeda cold air kit, you might see a little bit more. The shorty header bolts to the catalytic converter in the stock location, is coated to reduce under-hood temperatures and is made from 1 5/8-inch tubing. The list price is $319 and we sell a ton of them."

The exhaust system was equally impressive. The Magna Flow 2 1/4-inch stainless steel system impressed us with its superb construction and extremely good fit. "Our '00-03 Focus kit consists of a cat-back stainless steel system that is mandrel bent for improved flow and installs in the factory location with the stock rubber hangers," said Bruce Wayne, JOB TITLE, of Magna Flow. "The kit lists for $329, has a straight through mirror-finish muffler and is topped off with a 3 1/2-inch, double-walled, polished stainless steel tip. The kit fits all ZX3 and ZX5 applications."

After receiving the components above we began the install. Hooking up the Magna Flow 2 1/4-inch exhaust system and the Focus Central header is a simple task that you can do at home in your driveway and, with the exception of a few hard-to-reach bolts on the header, the task is really no sweat. For our job, we found ourselves at Crazy Horse Racing in South Amboy, New Jersey, where shop owner Chris Winter and lead tech Glen "One N" Knell would be lending a helping hand.

The first attack point was with the OE header. The ZX5 does indeed have a genuine header from the factory, but with all of the kinks and sharp turns in the tubes, not to mention their rather small diameter, the piece is far from ideal. There was plenty of room for improvement.

The new Focus Central unit has increased tube sizes and will fit onto the OEM catalytic converter. After removing the four 8mm bolts that hold the heat shield in place, we loosened the three studs that attach the converter tube to the flange of the header.

With the converter lowered and out of the way (there are also two bolts under the vehicle that support the converter which need to be removed), we unbolted the nine bolts on the flange of the factory header and lifted it out of the way. The header does come out with the power steering pump bracket in place but you will need to first remove the two outer studs (on the flange) or there won't be adequate clearance. This can be done with a six-point 8mm socket.

We then wrestled the Focus Central header in place. It went in rather easily, but due to the increase in tube size, it took a little extra effort to position it. After tightening down the nine flange bolts with a new gasket we reconnected the stock converter to the bottom of the header. Typical of most header installs, some of the flange bolts (at the head) are harder to attach on the Focus Central header due to the increased size of the tubes. We had a rather difficult time tightening some of the bolts (on the top of the flange) and had to resort to using a combination of wrenches, 1/4-inch sockets and 3/8-inch sockets to do the job. In time and with a little patience, they will tighten.

We then positioned the ZX5 on the lift where Knell and I assessed the exhaust situation before getting on with the removal process. Knell began by removing the rubber hangers, which suspend the system and let it hang so he could cut the muffler from the mid-pipe.

"You must cut the muffler from the mid-pipe or you will not be able to remove it," explained Wayne. "The factory welds the entire system together prior to installing it and there really is no easy way to remove it unless you cut it in half after the muffler."

Knell cut through the pipe with an electric saw in seconds and removed the entire system before discarding it. He then connected the Magna Flow mid-pipe to the flange on the OEM converter. Next, we slid the muffler in place and used the two supplied 2 1/4-inch clamps to hold the muffler to the mid-pipe and tailpipe.

Knell lightly welded the two slip flanges together (in addition to using clamps) to eliminate the possibility of them loosening up and developing a rattle or leak. This is not a mandatory step, but nevertheless, a good idea. Returning the Focus to the ground, we turned the key and revved the engine to 4000 rpm. The sound of the Focus Central/Magna Flow combo system was appealing to the ears. We were hoping it wouldn't mimic the sound of a Honda Civic (gulp!) and, fortunately, that was not the case. The roar was deep and strong.

Back On The Chassis Dyno
We made a series of dyno pulls to see what really worked and what was nothing more than high-flow hype. We are happy to report that both modifications (the header and exhaust) performed better than advertised and rewarded us with about what we expected in terms of power.

The first portion of testing came with the Focus Central header alone. Bolted to the factory exhaust, the header generated 103.9 horsepower and 110.9 lbs-ft of torque. All told, we gained a tick under four horsepower and just under six lbs-ft of torque at the wheels.

The next boxer to step into the ring was the Magna Flow exhaust system. It upped the ante as well, turning the rollers to the tune of 106.7 horsepower and 113.7 lbs-ft of torque. We gained a combined 6.7 horsepower and 8.7 lbs-ft of torque from the two parts--about what was advertised and around what we expected.

The Red Hot Chili Pepper is really starting to make strides. It has a new, lower stance and a killer rim/tire combo from Nitto and Konig. It's packing a 75 hp Nitrous Express wet kit for those 14-second quarter-mile blasts and it now has an improved exhaust note that rivals exotic Porches and Ferraris (alright, it's not that exotic).

Next up, we'll get our sweaty paws on an upgraded transaxle that is capable of living behind the nitrous hit. With the nitrous button depressed, our four-speed automatic did its best Elvis impersonation--it slipped, tripped and flipped when shifting through the gears on the gas, but we have recently been notified about more than one company who are tweaking Focus transmissions. On motor, the trans operates fine but with the gas, it's lights out. An improved converter and a refurbished automatic will no doubt be needed soon and should respond well to the juice. Look for a complete rebuild in the near future. Can we run in the 13-second zone without the aid of a turbocharger or hardcore internal engine modifications? We're sure going to try.