||This is what the
"Y"-Pipe looks like for the 1999 CA/NLEV Maxima.
The official name for this part is "Front Exhaust Tube
Assembly". Note it is a two-piece design which includes the
forward pre-cat as a separate assembly. Both the
Stillen and Cattman replacement pipes for CA/NLEV vehicles do not eliminate the forward
pre-cat, as they do on Federal Spec cars. It stays in place exactly
as-is and is necessary to maintain the car's OBD II compliance. The rear-pre-cat,
however, is removed completely from the aftermarket design. The car will
still pass emissions with flying colors, and will be a lot more
powerful. The mighty VQ30DE engine is dying to be unleashed, and
will be once the stock pipe is replaced.
||If the above illustration from
the 1999 Shop Manual doesn't give you a feel for how the 1999/2000 CA/NLEV
exhaust looks, this photo was taken standing directly in front of the
car looking straight down at the forward exhaust manifold. The
blue wire leads to an oxygen sensor which is installed in the manifold. The Federal Spec 4th-gen Maximas have the O2 sensor but
it is not as visible as the CA models. Also, the pre-cat is
surrounded by a heat shield so you can't actually see it. The
Federal Spec vehicles do not have the heat shield, since the pre-cat is
not attached directly to the exhaust manifold as it is in the '99/2K
||Here are the Nissan OEM
gaskets necessary to
install the Y-Pipe. The large, flat gasket goes between the Y-Pipe and
the catalytic converter. The smaller crush ring gaskets are for
the Y-Pipe connections to the rear exhaust manifold & forward
pre-cat . Note the crush
rings are different for the CA-spec vehicle. The smaller
crush ring (top) is for the forward pipe section. Nissan
part numbers are visible on the bags. Prices from Nissan
were as follows: Small crush ring - $2.76, Large crush ring -
$5.16, Cat gasket - $3.43. Cattman normally supplies crush
rings with their production pipes. They do not supply a
new cat gasket, which should probably be obtained from a dealer
||The second prototype Cattman Stainless Steel pipe
design substituted a small piece of stainless steel flex pipe
for the rear slip joint. The use of a flex pipe
helps greatly to isolate engine vibrations and prevent them from traveling
down the entire length of the exhaust during hard acceleration.
The front slip joint remains. The slip joint is extremely precise
and requires no welding or clamping to hold it in place. I chose to go the extra
step and have Cattman polish the pipe using a two-step process
which results in a show-like finish.
pictures show all of the pieces up close, and finally the whole
pipe assembled together as it will go on the
car. The slip joint is very precise and will be
"gas-tight" without any welding, crimping, or
sealing. Below is a series of shots showing the stock
Y-Pipe exhaust system before installation of the Cattman pipe.
|Before taking off the
stock Y-Pipe, both the main 3-way catalytic converter heat shield and
forward pre-cat heat shield must be removed.
nuts must be removed from the rear exhaust manifold. A
universal joint is necessary to get at one of the harder to
reach nuts, but it comes off no problem.
CA-spec 1999 and 2000 Maximas like mine, the forward pre-cat has
to stay put or the Engine Control Unit (ECU) will be very unhappy.
The front pre-cat needs to be loosened slightly at the forward
exhaust manifold in order to get the stock Y-Pipe out. It
is a little tricky. Note the forward O2 sensor
embedded in the pre-cat. This stays put as-is.
The stock Nissan Y-Pipe has the nuts built into it,
so when you put the Cattman pipe on you have to screw on 3 of
your own nuts to match the stock bolts. The nuts required
are 1.25 pitch, and can be purchased at any hardware
store. This picture shows
the bolts already removed.
||I chose to
replace the pre-cat bolts and the rear manifold nuts, since the
stock ones were a little rusty, and this was the second time the
stock pipe was coming off. While this is not entirely
necessary, it is certainly not a bad idea - and it will make you
feel good. It was necessary to purchase the nuts to
secure the Y-Pipe to the forward pre-cat. The stock Y-Pipe
has the nuts welded to it, while the Cattman pipe does
not. We used stainless steel lock washers to make sure
everything was tight.
the stock Y-Pipe removed from the car, compared to the Cattman
pipe. The rear pre-cat is
clearly visible as a bulge just aft of the front tube. The
Cattman pipe is a much cleaner design, as it is essentially a
straight-through pipe with no pre-cats.
||One of the
issues corrected with the second prototype was a slight
adjustment to the forward flange angle. You can see from
this picture that the new design mates perfectly to the forward
pre-cat with no gaps at all. One minor change that my
mechanic had to make was to replace the bottom most bolt with a
longer one, since the flange on the Cattman pipe is a little
thicker than stock. The stock bolt was not long enough for
the bottom hole.
||This shot simply shows
the new pipe mated up to the rear exhaust manifold, and the O2
sensor. The smooth bends in this pipe are really a work of
||The new Cattman pipe
with flex joint fit
perfectly to the stock catalytic converter. The stock
hanger is re-used, and supports the pipe at the converter.
We had to put a very small bend in the hanger to avoid a minor
rattle that was occurring when the car was floored from a
standstill. I don't plan on beating on the car like this
too often, but I had to explore the limits when I test drove
it. Bend hanger out of the way, and no more rattle.
bracket shown in this picture fit properly, but when the forward
section of the prototype pipe was reworked, the alignment of the
bracket holes with the car changed. Our solution was to simply
bend the bracket out of the way. The Cattman
pipe is so much lighter than the stock pipe without the heavy
pre-cat and heat shields that extra support is really not
necessary. This pipe isn't going anywhere. My
suggestion to Brian Catts will be to simply eliminate this piece
and save on the production costs.
||Here is the completed
pipe, looking very happy in its new home. There is a
definite and noticeable power gain with this pipe, without
any gain in noise output. As I had originally guessed,
the addition of this pipe to a totally bone stock Maxima exhaust
does not increase the exhaust note at all, and the flex joint is
perfect for eliminating vibrations. This is a totally
amazed at the quality and fitment of this pipe, especially
considering it was a prototype. I would like to thank Master Mechanic Joe, at Unorthodox
Racing for being the true genius behind this install.
He made it look easy, although this job is not something I would
recommend for an average do-it-yourselfer. Thanks also to
Brian Catts of Cattman
Performance, for finally getting so sick of me bugging him
for a stainless steel version of his Y-Pipe for my car, he had
to go out and make one.