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
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
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
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
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
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.
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.
2-You can see here the difference in collector shapes between the
merged and non-merged styles.
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.
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.
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
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.
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.
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.
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.
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.
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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