Pelican Technical Article: Installing a Performance Exhaust System Wayne R. Dempsey
Time: 6 hrs
986 Boxster (1997-04) 987 Boxster (2005-08)
Sport exhaust system
If your CATs are toast, replace your entire system with a sport exhaust system
Higher horsepower, throatier sound
Upgrade to engine performance software
This article is one in a series that have been released in conjunction with Wayne's new book, 101 Performance Projects for Your Porsche Boxster. The book contains 312 pages of full color projects detailing everything from performance mods to changing your brake pads. With more than 950+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any Boxster owner's collection. The book is currently available and in stock now. See The Official Book Website for more details.
Check out some other sample projects from the book:
One of the most important emissions devices ever invented is the catalytic converter. The converter works by altering harmful exhaust gases into more environmentally friendly byproducts. The first converters used a platinum-coated ceramic honeycomb or aluminum-oxide pellets coated with platinum to convert HC and CO into water vapor (H2O) and carbon dioxide (CO2).
Starting in 1980, a new type of converter design was introduced. These new three-way catalytic converters control HC, CO, and NOx emissions only when the air/fuel mixture is exactly set to 14.6:1. Without going into too much detail about fuel injection design theory, this air/fuel mixture is the absolute ideal for running the engine, and is the overall goal of almost all fuel injection systems. With the installation of these new catalytic converters, the addition of an oxygen sensor is required. The oxygen sensor (Lambda or O2 sensor) is connected to a computer that meters and controls the system to maintain as best as possible, this 14.6:1 ratio. When the car is running at this level, also called the stoichiometric mixture, it has reached a high level of efficiency and the catalytic converter is also working at its best.
Problems can occur for a number of reasons. If the oxygen sensor becomes disconnected or stops working, then the fuel control system can become confused and have difficulty metering the system. Usually this will cause the car to run richer than normal. Running the car in a rich mode instead of at its normal level can cause the catalytic converter to become clogged with soot from the exhaust system. As the converter, or CAT as it's sometimes called, becomes clogged, it can severely affect engine performance.
When you have catastrophic engine problems, you can sometimes damage your catalytic converters as well. With my 2.7L project car, the engine experienced a catastrophic failure, where coolant and oil mixed and were dumped into the exhaust system. There the mix sat for months or years. Very often, the remains of this stuff will burn off when you start your new engine, and many times the catalytic converters will recover. However, since this was a highly modified car with a 3.4 engine trying to pass California smog, we decided not to take any chances and instead installed the high performance system prior to taking it in for its smog check. Some components of coolant and engine oil are catalyst poisons: they coat the surface of the catalytic converter and render it less efficient or useless. Silicon and phosphorus, commonly found in coolant, and zinc additives, found in oil lubrication additives are all poisonous to catalytic converters. When head gaskets fail, coolant mixes with engine oil and is often deposited into the exhaust (as was the case with our project car's original engine). The result is that the catalytic converters can become poisoned and permanently damaged.
Most Boxsters have a total of four catalytic converters, which makes replacing them extremely expensive (early 2.5L cars only have two). The primary converters are monitored by the Motronic engine management system via the signals output by the O2 sensors. If one of your two primary converters is starting to go bad, then the Motronic computer (DME) will be able to figure this out and alert you with a check engine light (CEL) on the dashboard. Each one from Porsche costs about $1000-$1500, which makes replacing them extremely expensive (aftermarket ones are available, although are still expensive at about $300 each). You can find plenty of used ones on the market, but there's no guarantee that a used one is any good, and it's difficult to near impossible to test them prior to installation. The solution I recommend is to install a high performance exhaust system like the one I put on my project Boxster here. See the photo array for installation instructions.
Another alternative is to bypass the converter completely. While this will generate less restriction than a CAT, the tailpipe emissions will basically go through the roof. If you decide that you wish to remove the cats from your Boxster and replace them with headers, then you will find that your DME will generate secondary O2 sensor errors. This is because the system will see no difference between the readings of the primary and secondary O2 sensors. Using CAT by-pass headers and pipes in most states is legal only for off-road use, and should only be used for racing purposes. Removing the catalytic converter from your car will make it at output significantly more emissions than today's new cars. Doing so is not really worth the few extra horsepower that you will gain from polluting the air.
Troubleshooting CAT problems can be a bit frustrating. Some clues that the car may have a CAT problem include loss of power at higher RPMs and speed, even though the car idles perfectly fine. Many mechanics troubleshoot the fuel injection system first (indeed a smart place to start), but never really think that the problem might be a clogged CAT. If you remove the CAT, you should be able to clearly see through it. Chances are if you shine a bright light on one end, and you can't see any light through the other end, then it's clogged. The Boxster CAT has a right angle built in, so you can't really see directly through regardless, but some reflected light should be able to shine through. Cars that have recently had their oxygen sensor replaced are ideal candidates for CAT problems. If you purchase a car that has receipts that include an oxygen sensor replacement, be aware that the previous owner might have possibly driven the car many miles in a rich condition, thus damaging the CAT. If your car is having problems passing an emissions test, it may be a sign that your CAT is worn out and needs to be replaced. You may also be surprised at the additional horsepower that you might gain. Any clogs in the CAT will directly affect the efficiency and power of the engine.
It is very common for the nuts and bolts on older cars to rust, and make exhaust components very difficult to remove. This very well may be the case with your CAT. If so, then you might need to grind off the nuts and/or heads of the bolts to get the CAT off of the car. It's not an easy job, and it is complicated by the lack of room underneath the car. If you have extreme difficulty, then take the car to your local mechanic. The header bolts are very prone to breaking and if they are highly rusted, they should be heated up red-hot with an oxy-acetylene torch to assist in their removal.
Shown here is the Boxster Maxflo Exhaust manufactured by Fabspeed Motorsport and available from PelicanParts.com. This finely crafted setup is manufactured out of high performance T304 stainless steel and is CNC mandrel bent for optimum flow and fewer restrictions than Porsche factory exhaust systems. The Maxflo header systems feature 2 inch (50mm) pipes that connect to a dedicated true 2.25 dual muffler system (only one shown in the photo). The dual canister Maxflo exhaust system is low profile and utilizes secondary cat bypass pipes to save 30 lbs of weight compared to the Porsche factory system. Plus, the whole sound of the system is way cooler than the whimpy stock factory muffler.
The system utilizes the long, stock muffler mounting bracket that normally attached to the top of the stock muffler. Custom brackets attach to the existing mounting holes on the bracket (green arrow). A large stainless steel clamp is used to support the weight of each muffler from the bracket (yellow arrow). There are two brackets, one on each side (blue arrow, opposite side).
This system includes a pair of high-flow catalytic converters. As mentioned in the text, these converters are lighter weight and also are more efficient than the stock dual units designed over a decade ago. Use the stock manifold hardware (yellow arrow) to mount the header / cat unit with the supplied copper gasket (inset).
Here's a side shot of the new catalytic converter unit installed. These things look so good, it's a shame they are hidden underneath the engine. Connect the joints together using the supplied thick copper gaskets, and self-locking copper nuts.
The crossover pipes are attached to the ends of the catalytic converter / header assembly and joined with a clamp (inset). This allows some flexibility when installing the system. All cars are made slightly differently and sometimes rigid pieces of exhaust pipe will not fit perfectly without some give and take.
The secondary pipes that connect to each muffler have a built-in flexible joint. This allows vibration and chassis flex to be transmitted through the exhaust system without weakening the joints or causing annoying exhaust leaks. The secondary pipe is attached directly to the muffler via a heavy duty exhaust clamp (yellow arrow).
On the Maxflo system, an additional support bracket attaches to the lower part of the original muffler bracket on the transmission (red arrow). This helps support and retain the two mufflers via a set of brackets that attach to the large stainless steel muffler clamps.
There's not much chance of these joints leaking. Instead of using an exhaust clamp here, Fabspeed uses a high quality clamp that both joins the pipes together, and seals the connection. The inherent spring in the clamp assures that the connection will be tight regardless of temperature or vibration.
The rear tailpipes are dramatically different from the stock muffler, and the sound that comes out matches the look. It's a deep throaty, performance type sound that's not annoyingly loud, but makes you think, why didn't they design the stock system to sound like this? Actually, Porsche probably toned down the stock system to appeal to sensitive initial buyers, and to also encourage buyers to pay more to upgrade to one of their premium exhaust packages at the time of purchase.
Yikes! This is what our project Boxster looked like when we went to start it for the first time with the new engine. We had temporarily used the old exhaust system from the 2.7 motor, and all four catalytic converters were full of oil and coolant when we initially started it up. The mix of coolant and oil in the converters from the engine failure most likely rendered them inoperative.
Comments: I'm looking to replace the system on my 987.1 3.2S with a racing system club motorsport, track only use. We don't need cats but have to keep drive-by to about 103-105db. What would you recommend? Thanks.
February 8, 2014
Followup from the Pelican Staff: I like the fabspeed or AWE stuff. But not sure of the db output. Give our parts specialists a call at 1-888-280-7799. They can help you find the right exhaust.
Comments: I purchased the Fabspeed exhaust system headers on back in 2011. Since day 1 I have had problems with the exhaust mufflers and no help or recommendations from fabspeed. My problem is the connecting pipes between the two mufflers never fit correctly.On my two mufflers the male pipe has two slits. I have had two different shops try to connect them. However, the male pipe never went in far enough and the back end of the slit were exposed. Therefore I have to keep putting muffler puddy on the exposed slit.The pipe also keeps slipping apart.Looking at your muffler pictures,the female pipe currently has the slits for pipe expansion. It's obvious that the earlier versions were poorly designed. Have any of your customers with the earlier muffler design have this problem, and was there a fix? Like cutting down the male pipe?
October 24, 2013
Followup from the Pelican Staff: I have not heard of any issues. However with aftermarket exhaust it can be tricky to get a perfect fit at times. if you cannot get the connections to fit and they leak, i would take the vehicle to a muffler shop and have them make a sleeve to go over the exhaust and weld it. This might be your best bet. - Nick at Pelican Parts
Comments: wayne, do you guys have military discounts? I'd love to purchase the maxflo exhaust but it's a couple hundred over what I planned to spend. if not, whats the second best choice muffler for my 99 2.5L boxster?
May 2, 2013
Followup from the Pelican Staff: Give our parts specialists a call at 1-888-280-7799 and they can help you sort out the options for your exhaust system. - Nick at Pelican Parts
Comments: I just pulled the stock muffler on my 2001 Boxster 2.7 and had a Magnaflow pair put in instead. Can I also go back and remove the back cat's and just use pipe instead? I didn't see an o2 sensor on the 20cats near the muffler. Will it sound more viscous and better power? Is that the trick, eliminating the last 2-cats?
January 10, 2013
Followup from the Pelican Staff: I would not remove any of the catalytic converters, this is tampering with emission components. If you don't like the sound, you might want to try a different brand aftermarket muffler. - Nick at Pelican Parts
Comments: I've had the Boxster S race exhaust installed for about a year on my '05. I have been very pleased with fit, quality and installation ease. However, even though it sounds outstanding above 3K rpm, it drones badly below that. Any suggestions on reducing the drone, will header wrap on the two resonators work? Any other suggestions appreciated. TIA, Rick
December 16, 2012
Followup from the Pelican Staff: Header wrapr won't make a difference. I think you're going to have to live with the sound. - Nick at Pelican Parts
Comments: In figure 4 of the above article on the Fabspeed Performance Exhaust System, the caption states "these converters are lighter weight and also are more efficient than the stock dual units designed over a decade ago".
When you say "more efficient", does this mean that the emissions produced from these cats are cleaner or better than the original dual cat system?
September 3, 2012
Followup from the Pelican Staff: From what I am told, the CATs that are part of this system have a more efficient honeycomb construction, using updated technology, which allows for the use of only one CAT rather than two. - Wayne at Pelican Parts
Comments: Hi, will an after-market 986 exhaust stated for 2.7L-3.4L fit on my 2.5L 1997 boxster? What are the fitting issues? thanks in advance
July 10, 2012
Followup from the Pelican Staff: The mufflers fit well and will take most of the day to install. Give our sales department a call 1-888-280-7799 , they will help you get the right mufflers ordered. - Nick at Pelican Parts
Check out some other sample projects from the book: