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Performance Exhaust Systems

By Ryan Ballou

This being my first write up with SuperBeetles.Com, I guess a short introduction is in order. I've been involved in the VW hobby for almost nine years now. My first and only VW is a 1974 Superbeetle that I purchased my junior year in high school. Within a year I was already wrenching on it, learning it inside and out. Little by little it's gotten to where it is right now, a modest looking sleeper. No trailer queens here; chipped paint, rust bubbles, holes in the floor pan, but pull up next to me on the street and I'll give you a run for your money. Best part, it's my daily driver!

I've decided the focus of my first few articles will be bolt on performance simply because these are the most common modifications performed by enthusiasts looking for a little more power. My main focus on all articles however will be street performance, as in able to withstand daily use. This month I cover exhaust, probably the most common performance based modification out there. Just stand on a busy street corner for a few minutes and you'll see exactly what I mean.

The first question you need to ask yourself when choosing an exhaust system is, "What is your intent for this engine?" Do you have a stock 1600 and want something that sounds a little meaner, or do you have (or are building) an engine that's a little more serious? This will help determine the type and size of header you will end up with. For a stocker your best bet is a 1 3/8" extractor style header as it can utilize your heater boxes.

Next size up is a 1 1/2" header, good for larger bore engines (1776-1915) that keep the rpm's under about 5500 and have valves that are 40x35 and smaller. These are available in either a full merged design or extractor style. The difference between full merged and extractor is essentially the shape of the collector, the area where all four pipes come together. In a merged header, the four primary exhaust pipes taper into a cone section consisting of a ¼ of each primary as seen in the photo and then exit into a secondary pipe, usually part of the muffler assembly. In an extractor, the four primaries simply dump into a short cone. The other difference is that merged headers generally use slip joints for all the primaries. Meaning - the header comes in five sections; four primaries and a center/collector section. Extractors are usually three parts, the 1 & 3 primaries are separate, and the 2 & 4 primaries and collector sections are one piece. These use stock styles clamp at the 1 & 3 joints.

Using an extractor style exhaust will still let you use your heater boxes but you will take a performance hit for it as the boxes have a smaller ID (inner diameter) than the rest of the header. If you can sacrifice heat, then merged is the way to go for the best flow dynamics.

The next and most common size for maybe 90% of the performance engines out there is the 1 5/8" full merged header. This size will work from engine sizes 1776 and up, smaller if you turn serious rpm's. I'd say that you should be turning at least 6k rpm to justify this size. For smaller engines at least 6500-7k rpm. This size will support nearly every "street" combo you can throw at it. Serious racers turning in excess of 7500-8k (up to 10k) rpm will look to larger exhaust sizes of 1 3/4" and larger, but these types of engines are typical of your street driven VW.

Now that you've decided what size and possibly the style of header to use, you have a few options to consider. The driving force behind these options is your budget. Don't think that just because this is a simple bolt on that it has to be inexpensive.

First thing to consider is coatings. There are a variety of coatings available to keep your header looking and performing nicely. The ones I've come across are ceramic based, commonly called ceramic coated. The purpose of having a coated exhaust is to prevent rust, and keep the heat in the pipes as hot gases flow better. Secondly, by keeping the heat in, you keep excess heat out of the engine compartment if your seals aren't up to par. You'll be amazed at how cool the area around your exhaust is if it's been coated.

There are different grades available at varying costs. Don't be fooled into thinking all coatings are the same. HPC and JetHot coatings are arguably two of the best coatings available, as proven by their prices. Less expensive generic ceramic coatings are available at nearly half the price and will perform the same. However in most cases they won't last as long and may let rust through.

The next option to consider is heat. I said before that 11/2" was the largest size for stock heater boxes. There are now heater boxes available with pipes the same size as your 1 1/2" system to avoid the performance hit. If you want heat with even larger exhaust sizes, then there is only one source I know of, Gene Berg Enterprises. They are not cheap, and you'll likely be put on a waiting list, but if you want your cake and eat it too, they are the people to call.

Finally you have the option of a fully custom exhaust system. These are designed specifically for your engine and driving needs. Do a little research and you'll come across a number of companies that will work with you to custom fabricate an exhaust system just for you specifically. Those who have gone this route swear by it, but be warned this isn't cheap either. Paying a grand or more can be expected.

Custom designs can consist of stepped headers where the primaries are 'stepped' to a larger size before reaching the collector. These help to prevent reversion (reverse air flow, exhaust goes back in and intake charge blows back out) and keep the gasses flowing better. Reversion can be a problem when using cams with more overlap. Another design is the Tri-Y style or 4-2-1, whereas a standard header is a 4-1. That is, four primaries come together into one collector. A Tri-Y is where the 1 & 3 primary join, as do the 4 & 2 primary, and then those two pipes come together at the collector. These are known for making more mid-range power where the 4-1 style is known more for top-end. Again, all custom fabricated, and all expensive, but if you have to have the best, these are the options you should be discussing with your exhaust builder.

Now that you've got your header decided on, it's time to pick a muffler for it. Many times you'll be restricted by the orientation of the mounting flange at the collector of the header. Different manufacturers use different sizes and orientations, limiting your muffler choices to those that match.

Mufflers are a trade off, performance for silence. Probably the most common and style is the "fat boy" muffler. This is just a big muffler that hangs off toward the passenger side like a single quiet pack does. There are many different makes to chose from, far too many for me to cover. My vote is for the true "Phat Boy" muffler by A1 mufflers. It's a Magnaflow muffler pre-fabbed with collector pipe and tip. They flow very well, and aren't quite as loud as a stinger, close though. Long highway drives at high speed can cause some minor hearing issues if you have no sound deadening material, e.g. carpet, firewall tarboard, etc. In my experience, drives of over an hour long can cause some minor hearing problems but it's not as bad as the last concert I went to.

Other styles are the tried and true quiet pack or dual quite packs, hide away, and stinger. With the exception of the stinger, the other three will give a performance hit because they don't flow as well, but they are much quieter. The stinger still seems to be the winner when it comes to the 1/4 mile. It should be noted however that the closest in performance to a stinger is the Magnaflow AKA Phat Boy. If you want to get really fancy you can get a fully polished stainless steel Phat Boy from A1 mufflers in Santa Ana, Ca. like the one I have. It'll never rust and will last, as long as I don't bang it up on the street. Don't forget you have your coating options here too for rust prevention.

With your system now picked out, there are only a few details left before you can install your new toy. Hardware is the first thing to consider. As you will find out for yourself, when you step up to a larger header size, it can get really hard to tighten those nuts on exhaust studs. The best option here is to pick up some reduced OD (outer diameter) nuts. The standard wrench size for exhaust nuts is 13mm. Ask around at your local VW shops and you'll find that you can also get 12mm and 11mm wrench size nuts. I opt for the 11mm nuts myself since they are the easiest to install. For the collector flange, you may find that normal bolts won't work either since the head is also 13mm. My solution is to use stainless steel allen head bolts.

Then you have to worry about gaskets. The stock gaskets will only work well with 1 3/8" headers, 1 1/2" may have a problem, and anything larger will have a problem. The opening just isn't big enough. Do yourself a favor, skip the paper gaskets and go straight for the stamped copper gaskets. Open up the ID with a dremel tool or file so it's just a little larger than the exhaust port and test fit them to make sure they won't interfere with the opening. They have slots instead of holes so that if you develop a leak or just need to change them you can without removing the header. Best of all, they are completely reusable if you anneal the copper. When you anneal copper, you make it soft again. Throw them on a burner on your stove on high heat until they glow red, and then let them cool there. Wipe off the carbon that will flake off, lightly hit them with a Scotch-brite pad and they are ready to go again. Buy two sets and you'll always have one ready. You can get copper gaskets for all the primary pipes as well as the collector flange.

I'm going to assume you already know how to install a stock muffler; an extractor goes on exactly the same way. A merged header however is a little different. The first think you need to do is test fill all of the slip joints. If the header was coated these might be tight and you'll want to address this now. If they are tight, use some 320-grit wet/dry metal sandpaper and sand around the inside of the slip joint first since it's not visible. If you still can't get it to fit, start on the other pipe that slides into the joint, but only go about 2" back. You want it to slide in without too much effort, snug is good, loose is bad. A slip joint seals with heat, it expands when hot and seals itself. So the tighter it is to start, the better seal you'll get.

Once you know it'll all fit together nicely, start by installing the #2 & #4 pipes into the center section. First smear some anti-seize on the slip joints. They'll go on easier, and when it burns off, the carbon will help to seal the joint. While it's out and your finger is covered in it, smear a little on each exhaust stud too, just a little; it goes a long way. Now hang the assembly from the exhaust studs. Start the top nut on each side by hand just until they grab a few threads; this will keep the assembly from falling off. Don't forget washers under every nut/bolt. Now pick either the #1 or #3 J tube and start it on. You may have to work it on so that it will sit flat on the mounting flange and slide all the way into the joint. Once both the J tubes are started, you can start working the rest of the nuts on. Go as far as you can by hand. You should be able to tighten them all by hand to the point where each mounting flange is flat against the gasket on the head. Likely causes of a flange being cocked are a slip joint binding up on you.

Once the entire header is installed, it's time to install the muffler. I like to just barely start each bolt at the flange to get some threads into the corresponding nut. Don't forget the anti-seize or washers here. Once the muffler is hanging you can attach whatever style hanger at the muffler that you are going to use. The mufflers generally have a mounting tab welded on them just for this purpose. I use a rubber hanger that bolts to my fender-well. Mount and bolt the hanger in such a way that it suspends the muffler in the correct position before you tighten the flange bolts (it should still be hanging by them). This will assure the load is evenly distributed between the flange and the hanger. Too much weight on the flange can cause welds to break over time from stress. Once the hanger is in place and bolted on, you can finally tighten the flange bolts at the collector.
Now all that's left is to start the engine up, let her rip and drive, it like you stole it.

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1-Here's an example of an extractor style header. It's my old 1 1/2" header that's been out of use for some time now.
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2-You can see here the difference in collector shapes between the merged and non-merged styles.
Click 3-Rust spots showing through here took about 1 year to develop. This can be expected when you go the less expensive route on ceramic coatings. The muffler, however being stainless steel will always polish back to a shine.
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4-My polished stainless muffler from A1 when it was new. The stainless casing will discolor with a golden tint over time from the heat.
Click 5-A small assortment of nuts in varying ODs. You can see the difference in head diameter between a normal 13mm head bolt and an allen head bolt. Click 6-Here you can just make out the clearance between the 11mm OD nut and the header pipe at the head. As it is, I can just barely fit a box end wrench on these. 13mm would only be possible with an open-ended wrench, which is more prone to chewing up the nut. When running even larger sized headers, this clearance gets so tight that the nut itself barely clears the pipe.
Click 7-Copper manifold gaskets are the way to go. The will not blow out and can be reused over and over. This one has been opened to fit my 'big' heads and therefore is quite larger than the exhaust port seen here. When matching these, you need only be about 1/16" larger in diameter. Click 8-You can see the slip joint here and where I sanded too far back to make it fit right. The lack of carbon deposits around the joint proves these don't leak if they fit snug. Notice the thermostat barely clears the pipe. I had to cut half of its mounting fixture off for it to fit properly. With a ceramic-coated exhaust, not enough heat is transferred to the bellows to render them useless. They will open only slightly faster than normal. With a non-coated exhaust or a black coating, the bellows will likely open much faster hampering warm up times. Click
9-The previous picture and this illustrate the need to cut your cooling tin to fit around a merged header. Non-merged headers don't have this problem.
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10-The hanger shown here was provided with the muffler. It looks to be nothing more than a strip cut from a tire with holes punched in it. This extra support keeps the welds at the collector from breaking with time.
Click11-Completely installed you can see that this particular system retains a good deal of ground clearance. Fact is the only piece I've hit in driveways is the 'U' bend where it sticks out past the bumper. The added distance from the axles make this the only spot to worry about. The farther out it is, the more likely it will hit. The muffler itself has only taken one dent from a rock on a dirt road.  

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