Cattman Stainless Steel Y-Pipe
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Y-Pipe Prototype # 1 ] Y-Pipe "Quiet Flex" Prototype #2 ]


This section documents the installation history of two different prototype "Y"-Pipes on my 1999 Nissan Maxima SE with the CA/NLEV restricted emissions package.  Aftermarket Y-Pipes for the Maxima are designed to replace the somewhat power-robbing design of the stock unit, which contains two pre-catalytic converters and possesses a poor flow design which does not incorporate smooth mandrel bends.  There are currently two manufacturers of aftermarket Y-Pipes for the Maxima: Steve Millen Sports Parts (Stillen) and Cattman Performance.  Cattman Performance is the only manufacturer of a stainless steel version of this pipe.  With the exception of a supercharger, NOS, or other forced-induction system, replacing the stock Y-Pipe on the Maxima will give a larger horsepower gain than any other single performance modification while still keeping the engine normally aspirated.  Estimates are anywhere between 15 and 25 hp.

After living with the stock exhaust system for about a year and a half, I decided I wanted to get more power out of the beast by replacing the main exhaust tube (Y-Pipe) with a less restrictive aftermarket option.  From doing research and reading the message boards on the Internet, I knew Brian Catts of Cattman Performance made a stainless steel pipe, and Stillen made an aluminized mild steel version.  There was never any doubt that I wanted the stainless steel version, but I discovered that Cattman Performance did not make a stainless pipe yet which fit the slightly different design of the 1999/2000 Maxima with California Emissions.  This was not good news, but it motivated me.

Brian Catts of Cattman Performance probably regretted the day I decided I was going to harass and bother him into developing a stainless steel pipe for my car because it meant a relentless barrage of emails and lengthy technical correspondence which lasted for almost three months.  I offered the use of my late model Maxima as a testbed to prototype a stainless steel Y-Pipe, and this was where the fun began.  I knew that I might be in for a rough development process, since the pipe had never been made or fitted to this vehicle type before.  There was an added complication that Cattman Performance is located in Arizona and I live in New York.  We agreed that I would foot the cost of the installation, provide the vehicle, and Cattman Performance would give me a discount on the pipe.  This sounded like a good deal to me, since all I really wanted was for the pipe to be developed.  Cattman had the expertise but no CA-spec car, and I had the car but no pipe.  A match was made.  Although it was a lengthy process with some difficult moments, I have to commend Brian Catts for really coming through on this development project.  Brian met all of my requests for information and demands with cool calm professionalism, and produced an incredibly high quality, aircraft-grade part that will no doubt last a lifetime.

About the Y-Pipe Design

Although all 1995-1999 Maximas are considered "4th Generation" and for the most part are identical mechanically, the Y-Pipe on the 1999 California Emissions vehicles was an exception.  In 1999 Nissan went with a slightly different design for the CA/NLEV Maxima, which the '99 cars share with the 5th-Generation (2000) Maxima, rather than its closer 4th Generation cousin, the '95-'98 Maxima.  While all '95-'98 Maxima Y-Pipes are one-piece designs, the '99/2K CA-spec Y-Pipe is a two-piece assembly composed of a rear section and a forward pre-cat which is attached directly to the forward exhaust manifold.  Apparently, Nissan was getting a jump on the new exhaust design for the 2000 CA-spec Maxima, and incorporated it into the 1999 model year.  

Aftermarket Y-Pipes for the '99/2K CA-Spec Maxima do not replace the forward pre-cat, since it is required in order to maintain the car's OBD II compliance.

Cattman vs. Stillen Y-Pipe

Until the pipe for my vehicle was prototyped and manufactured, Stillen was the only manufacturer of an aftermarket "Y"-Pipe for the '99/2K CA-Spec Maxima.  Unfortunately, Stillen's pipe is not stainless steel, which essentially eliminated it for me as a serious replacement candidate.  Stillen's pipe also has a reputation for producing a loud "hissing" noise (also referred to as "bees-in-a-can") which is caused by the type of flex joint Stillen uses.  The hiss can be quieted by wrapping the flex joint with header wrap, which eIiminates about 90% of the noise.  Why a large company like Stillen, with the resources at their disposal, does not make a stainless steel version of this pipe with a quiet flex joint escapes most Maxima enthusiasts, myself included.  Below are some pictures of the Stillen Y-Pipe.  Stillen's latest design is a generic model which will fit all Maximas from 95-2K regardless of California Emissions.  Thanks to "GR Racing" on the Maxima forum for these nice pictures.

Editor's note: As of this writing (August 2000) Stillen has modified the configuration of their Y-Pipe (see pictures below), and it no longer has the reputation for making its infamous "bees in a can" or hissing noise.  The Stillen pipe no longer employs equal length tubing runs for the front and rear manifolds.  

The piping design of the Stillen and Cattman pipes are now virtually identical, although the collector on the Cattman pipe is still superior.  As was mentioned, the Stillen pipe is still not available in stainless steel although as of early 2001 Stillen made their pipe available with a high-temperature coating.  Judging by the volume of problems reported by customers of the prior Cattman Jet Hot Coated Y-Pipes which Cattman no longer produces, I wonder about the reliability and longevity of Stillen's coated pipe.  Time will tell.


Stillen Y-Pipe

StillenYPipe1.jpg (127154 bytes) StillenYPipe2.jpg (127058 bytes)
StillenYPipeFlex.jpg (43991 bytes) StillenYPipeFront.jpg (49755 bytes)


Stillen High-Temp Coated Y-Pipe

Coated Y-Pipe.jpg (21121 bytes)


I was fortunate enough to establish a working relationship with Brian Catts of Cattman Performance, and together we initiated development and prototyping of a stainless steel "Y"-Pipe for all 1999 and 2000 Maximas with the CA/NLEV emissions package.  The pipe was custom-manufactured by Cattman Performance in Arizona, using a stock pipe as a model.  The pipe was then polished using a two-stage process which results in a show-like finish.


I chose to have the pipe professionally installed by Unorthodox Racing in West Babylon, NY.  Although the "Y"-Pipe install is not impossible for a do-it-yourself-er, I think it is well worth the money to have a pro do it simply because of the accessibility problem in getting underneath the car.  I have a phobia about being crushed by my car, so I hired the same experts who installed my Underdrive Pulley.  They did a great job, and it only cost me $100, which I am gladly willing to pay to sit back and eat donuts / take pictures while my Y-Pipe was installed.  Since this was a prototype effort there was even more reason to be in the controlled environment of a professional tuner shop in case any fitment issues arose.

A little about the prototype effort

Any time a prototype effort is undertaken it has to be expected that there might be a few bumps in the road.  The development of this prototype pipe went very well but there were a few minor issues which resulted in corrections being made by Cattman Performance, and a second prototype was shipped to NY and re-installed on the vehicle.  The fitment of the original pipe was absolutely perfect, but it was discovered that the lack of a flex joint was causing some harmonic vibration problems when the car was under heavy acceleration from a standstill.  It was mutually agreed that a flex joint was necessary, and the pipe was retrofitted with a stainless steel flex at Cattman and re-installed by Unorthodox.  There was also a very minor mating discrepancy with respect to the forward flange angle, which was corrected on the second prototype.

I decided to document both the original prototype and the modified prototype installations for the sake of completeness, and so that those out there who are interested in the process may see just how much effort goes into it.

Prototype Y-Pipe Installations

Y-Pipe Prototype # 1
Y-Pipe "Quiet Flex" Prototype #2


The addition of this pipe to a stock Maxima will result in horsepower gains of anywhere between 15 and 25.  This is power you can definitely feel, and let me tell you - it makes a big difference from the driver's seat.  The stainless design with the "quiet" flex joint results in no noise increase at all, unlike the infamous Stillen "hiss".  There is no hiss, rattle or other noise with this pipe.  If you have an aftermarket muffler, the car's exhaust note will be amplified but this is due to the muffler and not the Y-Pipe.  I think this was a very worthwhile power upgrade which is higher quality than stock, more powerful, and will probably result in a slight M.P.G. increase due to the elimination of the pre-cat and the smoother exhaust bends.

If you have any questions about this pipe or my ownership experiences with it, please contact me at  I will do my best to answer.

Greg Prete      6/5/2000


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