Prototype Version of Streettracker Anvil Exhaust
 

 
Comments on Prototype
 

 
For what its worth, I like the look.  The lines follow the bike well.  The diameter of the pipe and the bends are aesthetically pleasing.  That has nothing to do with performance, but it is a nice element.
 
Installation took a little work.  As we already talked about, the outside diameter  of the pipe stub that you switched to on the front header was too large for the Y.  I ended up using a sanding wheel and fiber grinding wheel on the dremel to shave the header tube down a shade, and ream the Y slightly.  It ended up being a tight fit but once the headers were installed and lined up.  With the aid of a wood blockand hammer, and my son, I tapped the Y on.  No need for springs to hold that in place now!  The manifold flange on the front header was also tough to get on.  The outer collar on the front header was just a tough large and the end of the pipe had a rough cut.  The rear header fit was fine in the Y. 
 
Also, I have the HD LED turn signals installed.  The control module mounts on the seat tube behind the rear cylinder.  The angle of the O2 sensor on the rear header tube was a bit too far to the rear and would not allow installation of the header pipe with the LED module in place.  I installed the pipe by temporarily wire tying the module out of the way.  I snapped some pics of the interference, but if you rotate the rear O2 sensor down slightly, or move the sensor bung about 1/2" toward the rear cyclinder on its existing line, I think you should have adequate clearance for the LED module.
 
I liked the forward angle of the front O2 sensor.
 
All the other header flange angles seemed good to me.  I use a 1/2" socket on a 1/4" drive extension to tighten and torque headers, and the spacing was good for this. 
 
There are plus'es and minus'es to the single tube that connects the exhaust can to the Y.  I like the excellent clearance to the rear swingarm and the way it brings the exhaust can out away from the rear shock.  I run Ohlins with riser blocks and clearance was good.  However, the way this tube bends up toward the exhaust can, interferes with my right foot.  I ride with the  ball of my foot on the peg, and I can not do this with the current bend of the tube.  My heel hits the tube.  I simply shifted my foot forward to get to the dyno,.  Also, while I only have a size 10 shoe, a fellow with a larger shoe could potentially hit his heel on the pipe even with his instep on the peg.  You may want to consider a different bend for this rear tube, or if it does not detract from performance, add a few inches to this tube and give it a different angle to allow for riding with the ball of the foot on the stock pegs.
 
I do not have stock rear pegs, so I bent an "L" to use the OEM rear exhaust hanger and the mounting loop for the exhaust can.  This worked fine, but you might want to consider offering a replacement rear exhaust hanger that brings the attachment point in line with the rear of the exhaust can without having to use an "L".  Also, I do not know if the mounting loop that came with the exhaust can is supposed to be matched to it, but the diameter is slightly large and the exhaust can is free to rotate slightly in it. 
 
All in all, for a prototype, this exhaust was easy to install.  The front header tube/"Y" diameter issue is just a quirk of the prototype, but you may want to consider repositioning the rear O2 sensor to allow for installation of the HD LED kit that some riders will have.  Also, you may want to alter the bend of the rear tube, so that riders can bring their foot up on top of the stock pegs without resting their heel on the exhaust can.   And for a high performing pipe, it is a very quiet exhaust system.  I did not get a chance to take my noise meter to it yet, but I can tell that it is much quieter than other comparable performing pipes.
 
 

 
Pictures
 

 
Here are the header tubes loosely installed.  I had to stop here for a moment and deal with the interference between the rear O2 sensor and the electronics module for the HD LED turn signals.
 

1Headers.JPG
Header Tubes

 
 
Here is a look at the rear O2 sensor.  If the rear sensor were angled forward, or perhaps downward about 30 degrees, it should clear the module.  Alternately, moving the sensor bung about 1/2" toward the rear cylinder might also fix the issue.
 
 

2Sensor.JPG
Interference with Rear )2 Sensor

2aSensor.JPG
Interference with Rear O2 Sensor

 
 
I used the OEM rear bracket to hang the exhaust can.  I fabricated a short "L" bracket as a hanger.  Alternately, replacing the OEM bracket with a custom one that angled more forward would provide a more stable mount.  This particular mounting loop was a bit loose on the exhaust can, and allowed the exhaust to rotate a bit during riding.
 
 

3ExhaustBracket.JPG
Bracket

3aBracket.JPG
Bracket

3bBracket.JPG
Bracket

 
 
As mentioned, the "Y" took a bit of "finesse" to get on but once in place the fit was fine.  Also, it was tough to get the exhaust flange on the front header tube.  The outer diameter of the welded lip on the pipe made for a very tight fit.  Also, while the front header tube seemed to give a good seal in the gasket, the end of the tube had a very rough cut.
 
 

4Headers.JPG
Installed

 
 
Here it is fully installed.
 
 

5Installed.JPG
Installed

 
 
The minor issues I noted with install should just be prototype quirks.  But it would help installation for some owners if the rear O2 sensor were adjusted to be compatible with the HD LED turn signal module.
 
Plus, the tube between the "Y" and the exhaust can gives excellent clearance to the frame.  Unfortunately the current bend also interferes with riding with the ball of one's foot on the stock footrest.  It would be helpful if that pipe were re-bent to give more clearance for riding with the ball of the foot on the footrest, and/or for people with larger feet.
 
 

 
Noise Level
 

 
This prototype exhaust system is one of the quieter performance systems that I have seen.  The deep sound is pleasant, and I could tell from the sound of the engine noise that the exhaust noise was lower than other performance pipe systems.  It was louder than stock and the Torque Hammer with its noise silencer, but quieter than all of the other aftermarket exhaust systems I have tested.  While it's tough to hit the rpm point exactly the same for each pipe, the following tabled give a relative look at the sound levels using a digital sound meter (measured outside in free space, at 1 and 2 meters from the end of the exhaust can).
 
 

 
Engine Speed

 
dB @ 1 meter
 

 
dB @ 2 meters
 

1,000 RPM

100 dB

96 dB

3,000 RPM

109 dB

105 dB

 
Noise comparison against other full exhaust systems
 

 

1,000 RPM

3,000 RPM

 
Exhaust System

 
dB @ 1 meter
 

 
dB @ 2 meters
 

 
dB @ 1 meter
 

 
dB @ 2 meters
 

Stock (OEM)

91 dB

87 dB

98 dB

94 dB

Drilled Stock

93 dB

90 dB

100 dB

96 dB

D&D 2-into-1 header with prototype exhaust can

 

98 dB

 

109 dB

Streettracker Anvil (Prototype)

100 dB

96 dB

109 dB

105 dB

Termignoni 2-1-2 without silencer

102 dB

98 dB

   

Torque Hammer w/silencer

96 dB

92 dB

111 dB

107 dB

Torque Hammer without silencer

100 dB

96 dB

114 dB

110 dB

Vance and Hines 2-1-2 Widow

102 dB

98 dB

112 dB

108 dB

 
Exhaust tube sizes
 

 
To give you an idea of the difference in diameter between the exhaust systems, I measured the Anvil headers at about a 1.xx" internal diameter, and about 33" long.
 
The Termignoni headers start at an internal diameter of 1.572" and in about 3 1/4" it step up to 2.038".  The pipe continues at the 2.038" diameter to the collector (total header length = 34") where it combines into a single 2.5" ID pipe that later separates into the system's dual exhaust cans.
 
The D&D 2-into-1 exhaust headers start with an ID of 1.450" which steps up after about 30", to an ID of about 1.6".  This diameter continues for approximately 12" to the collector where the headers combine into a single exhaust can.  (Total header length about 42".)
 
The "standard" Torque Hammer has an ID of 1.554".  (The larger diameter prototype Torque Hammer has an I.D. of 1.670", which appears to be the largest diameter thinwall SS  tube which can fit through an OEM exhaust flange.)

 
Performance
 

 
I hate commenting on the feel of a pipe without doing a dyno comparison.  Too many guys attribute non-linear power response, to improvements in a part of the RPM band.  Most of the time it is more likely to be loss in one area simply making it feel like a slight surge in another part of the band offers an improvement.  But, I certainly did have the feel that this pipe boosted torque right off idle and contributed to smooth powerful low rpm performance.  The bike just seemed to accelerate more smoothly under partial throttle with this pipe.
 
Following up on the dyno, the peak power numbers were good.  The following chart is a look at a number of runs.  The TMax map that I was using was actually a pretty good match for the pipe right off the bat.  I rode about 50 miles on the way to the dyno and tried to hit a wide range of throttle points.  Then I ended up doing close to 50 miles on the dyno, and both auto-mapped and manually adjusted the map several times along the way, to hone in the fuel offsets.  The dyno runs in the below graph show the consistency of the performance once I got the map where I wanted.  The variation in the AFR lines is not bad mapping on the TMax part, but rather my experiments to try leaner or richer AFRs in different areas to see whether power was significantly affected.  It just shows that once the AFR was in the neighborhood, performance was very good.  AFR corrections provided minor HP and Torque improvements, but nothing radical.
 

Streettracker2.jpg

 
Performance was very good in comparison to other pipes.  Two of the better pipes that I have tried are the D&D 2-into-1 header pipe with a custom exhaust can from Zippers, and the V&H Widow 2-1-2.  Here is a graph of your pipe against those two pipes.  Yours builds torque more quickly below 3,000 rpm and scored the highest HP figures of all pipe combos that I have tried.
 

StreetrackervsDandDvsVandH.jpg
Streettracker vs D&D vs V&H

 
"Torque Hammer" is a great marketing name, but Dris' pipe is not one of the strongest exhausts for that purpose.  Just for comparison, here is a look at your pipe against Dris' production pipe with the noise silencer installed.
 
 

StreettrackervsTorqueHammer.jpg
Streettracker vs Torque Hammer

 
And, I can send you data comparing your prototype to the stock, drilled stock, and Termignoni 2-1-2 - but your pipe gives much better performance than all of these on my engine build.
 
I'd expect, with the intake tweaks that I tried separately, your pipe ought to help my engine break the 100 HP barrier also.

 
Conclusion
 

 
Don, I would say you have a winner.  It is a good looking pipe with a nice performance curve.  Not everyone will like how quiet it is, but the noise level is both reasonable and I would think it would pass European noise level checks.
 
With an adjustment to the rear O2 sensor to eliminate possible interference, and a tweak to the rear tube to allow variations in foot placement, it should be a great all round pipe.  Made out of thinwall stainless and coupled with a rear hanger that allows for easy install without the rear passenger pegs, it would be just about perfect.  I'm guessing that the ability to build good peak HP cost the mid-range slightly, but if there was a way to keep that top end and add a few ft-lbs through the mid RPM area, you would have an unbeatable pipe. 
 
Only considering foot placement, and not impact on performance - one thought for that rear tube might be to extend the lenth about 4" - 6", and let the single tube extend straight out in line with the header tubes for a couple of inches before angling it upward at a slightly steeper angle.  Alternately, maybe there is a way to bend that single tube so that it just drops the bend that enters the exhaust can about 2"-3."  I don't have the rear peg set installed so I don't know what this would do in terms of using that rear peg bracket as an exhaust mounting point.  But, I would expect this routing to still clear the passenger's footpegs and also leave a little more room for passenger shoes..  Plus, with an extra couple of inches of tube length, this should push the exhaust can back just far enough that the rear OEM exhaust hanger could be used with the exhaust mounting strap to hold the exhaust can at the rear.   So, you might want to consider a different bend for the rear single tube, or  - if it can be extended and keep in tune with the exhaust wave - adding a little length to the tube with a different bend, to clear the heel and shift the mounting point to the rear.  Just some thoughts...
 
A very nice job!  Heck, I might even want to permanently run one of your pipes, once you get it into production!!
 
Wiill talk more later, and get you the dyno runs and other info in a format you can use and tweak.
 
 

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