Introduction:

Looking for more ooompf than the Team Moon or other aftermarket exhaust provides?  On the track, I want as much as I can get.  So this is the first step in my solution to the problem - get rid of the cats and muffler and run open headers (almost).  Since the stock Spyder header points straight down, you could simply remove the catalytic converter and go run (leaving the muffler in or taking it out, depending on how difficult it is to take out).  I wanted a solution just a step up from that, so off to the speed shop I went.

Bill of Materials:

The parts to make this are few and they are relatively inexpensive.  The two major components are the flange material and the J-Bends.  I am lucky to have a speed shop nearby that stocks J-Bends in various sizes.  Note that I chose to use mild steel for the prototype.  Using stainless would add about $25 to the cost of each J-Bend ($50 total).  Even if I was to make one out of stainless, I would probably still use mild steel for the flanges just to avoid the tooling costs and difficulties.  And even though the materials cost is only about $100, the tool costs will run you well over $1000.

The basic steps I did were to first remove the cat and muffler.  I then traced a pattern of the cat to header flange and transferred the pattern to a piece of 1/4" steel plate.  I then cut out the plate with a torch and used a bench and die grinder to clean up the edges.  The actual pipes in the cat were just over 48mm, so 1 7/8" was a really close fit.  I tired to mimic the design of the catalytic converter flange in every repect - extend the pipes up into the header and get them centered as closely as possible.  I also angled the bends upwards to 110 degrees, not just horizontally to 90 degrees as you might expect.  Well, after completing the project, I would probably do just a 90 degree bend and save one 1 7/8" J Bend and a ton of aggravation getting the compound angle of the merge exit to the tip just right.  You will cut the J bneds at 110 degrees (or 90 degrees) and cut all but 3 1/2" of the straight section off.  Save what you cut off to make the merge.

The next major step is to get two small sections of straight tube and make a merge.  Two 1 7/8" sections will merger together into a 2 1/4" outlet.  You make diagonal cuts on two lengths of tubing about 3" long and keep trimming, grinding, and pounding until it all fits just right.  The next step is to weld the two halves of the merge together and grind it smooth inside and out (mostly inside).

Now you can fit the merge to the 110 degree sections of J-Bends in prepraration for welding.  Since the J bends extend through the flange, I used three bolts in the flange bolt holes with the proper number of washers as shims so that when the flange is on a flat surface and the j bends are put in their holes, they will extend the exact distance needed though the flange to mate up with the inside of the header outlet.  This is about 1/4".  With everyhting held in place, I used masking tape to hold everything in place temporarily, then it's off to the welder to takc it up.  Once the tubing is all tacked up, then remove the masking tape, re-check the fit, and then adjust it and weld it up strong.

Now it's time to fit up the first half to the car and check to see if the height and/or angle are ok and that it clears the cross member enough.  The simple way from here it to weld a straight piece of pipe straight out the back if you only did 90 degrees.  But I wanted it to look nice, so I used a 2 1/4" J bend to shift the pipe over 4" to the center of the car before exiting.  If you go straight out, you will be right under the right edge of the license plate (US plate).  I also angled the tip down 4 degrees for extra bumper clearance and just to give it a unique look.  If you went 90 degrees instead of 110, then you could put any angle you wanted to on the tip - horizontal or slightly down or slightly up.

So now the aggravating part of getting the outlet over 4" and getting the right up/down angle and making it all fit.  My J bends were 7 1/2" radius, so 4" offset is not a full 90 degrees - more like 55 degrees - or even longer if you are also going slightly up or slightly down.  Anyway, get everything cut and grinded smooth and tacked up again for a final fit.  Once everything looks good, weld it all up.  I left the outside of the tip just even with the back of the bumper.  Most tips would be set in an inch or two, so this one sticks out just a tiny bit more than most others.

One thing that is obviously omitted is the third oxygen sensor.  Since this is a track only exhaust system, I did not bother to put an oxygen sensor bung in.  They cost about $6 and would be easy to add, I just did not bother to do it.  The CEL will not come on with this setup if you are careful.  The third oxygen sensor will only trigger a CEL after it is detected bad for two "trips."  The computer defines trips as a convoluted series of idle and non idle for minimum periods of time.  On autocross, you never have the engine running long enough for a trip to trigger.  On a track, you would eventually trigger a CEL, but the particular codes thrown do not put the ECU in limp mode, which is good.

When installed on the car, I do not use the crush gaskets that the catalytic converter uses.  Since there is so little backpressure on this exhaust, I do not care if there is a tiny leak.  It's not like I could hear a leak anyways.  The other thing mentioned above, is I completely disconnect and remove the O2 sensor from the car when this exhaust is on.  No sense in having another 6 ounces weighing you down.  

It takes the catalytic converter about an hour to cool down to the point where you can handle it.  So that means you need to allow at least 1 1/2 hours to have the exhaust swapped on or off.  Typically, I will show up to an event as early as possible, be changing tires, prep the rest of the car (numbers, floor mats etc) register, walk the course, then swap the exhaust as the last step.  Tire swap and prep and registration usually take an hour so I should have enough time to make the swap unless problems arise.  I bring extra studs and nuts just in case something goes awry taking the cat off.

The Finished Product

Performance and Testing

So just how well does it perform?  Well, it weights in at a mere 7lbs.  It replaces the 27 lb stock muffler and the 17 lb catalytic converter.  So that's a cool 37 lbs saved from the rear of the car.  That's a pretty darned good start.

As mentioned before, it was recorded at 98 decibels, so that's how the name became Cyclops 98.  The peak volume measured is 99 decibels at 6000 RPM, dropping to about 94 decibels at 4000 RPM under full power and 85 decibels at cruise.  That's above the OSHA limit for sustained exposure to noise.  Hearing loss can occur in as little as one hour at those levels.  Now add a radio on top of that and you can see why this is not a good street exhaust (not to mention the legality).

Power wise, there is a noticeable gain across the whole RPM range.  Most notable is the power above 6000 RPM.  On the stock engine, there is a noticeable drop in power above 6200 RPM up to the rev limiter.  That decrease is much less pronounced and virtually gone so that the rev limiter comes up on you much quicker than on the stock engine.  It takes some adjustment in shifting to get the feel for shifting a little earlier to avoid the rev limiter.  Not a bad trade off.