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[North Star]

Ok, I know the Fullsac DX pipe is the best thing since sliced bread and all that, and I know this is frequently discussed but I'm looking for some hard facts (as in dyno sheets, not everybody says so, so it must be true info).

My GMR 113 build is being assembled locally, and I'm getting a dyno tune next week, so I want to make a final decision that I will stick with. For reference, the 113 build includes ported heads and a SE 58mm TB with 5.3 injectors.

What I'm trying to compare is a 2009 OEM headpipe that's been ceramic coated vs a Fullsac DX, paired with Rinehart mufflers (4" body, 2.25" cores). Key to mention is mine is a never-came-with-a-cat OEM pipe, not one that has had the cat removed, so a 2011+ de-catted header with possible cross-talk issues does not compare to what I have.

I'd love to see a dyno comparison, but I don't think any exist. Frankly, I've run both, and there is no seat of the pants difference. In fact, after my last cam change and a switch from my OEM to the DX, I actually got a new low end torque dip. Maybe that was the combo of parts, but I wonder...

The OEM merge collector chamber (or whatever you want to call it) is not small or restrictive looking, and in fact looks bigger than 2 small pipes crossing in an "X" pattern.

I suspect that Fullsac and Fuel Moto headpipes are really meant to benefit those with the 2011+ OEM headers, because removing the cat from those can cause the cross-talk issues, and it turns it into a pipe that is not used as designed. The 2009 OEM is designed to be catless, and I seem to recall some posts years back that it actually is a good performer.

In fact, I suspect the OEM squish pipe may be beneficial, as it makes the pipe perform a bit more like a 2-1 by restricting the flow to the left side. Most say HD did that for clearance reason, but again, I wonder. What I do know is that older posts by Fullsac said there is no difference with the squish pipe vs the full size cross under, and that it was only created due to customer demand.

Steve from Fullsac should be the one guy that would have some dyno charts to compare the two?

My end goal in all of this is to justify selling the DX pipe for a good buck (locally in Cdn $ especially), and run my OEM that I spent $250 getting ceramic coated awhile back, all with little or no detriment.

And if the 2009 OEM is proven to be a bit more restrictive, I wonder if that would actually equalize the fact that my Rineharts are a little too wide open, and make the OEM/Rinehart similar in flow to a DX/Fullsac 2" cored muffler (which I actually own, but don't want to run).

Long winded post, so thanks for reading, and let's see some hard facts on paper!

[Fullsac Performance]

Ok, I know the Fullsac DX pipe is the best thing since sliced bread and all that, and I know this is frequently discussed but I'm looking for some hard facts (as in dyno sheets, not everybody says so, so it must be true info).

My GMR 113 build is being assembled locally, and I'm getting a dyno tune next week, so I want to make a final decision that I will stick with. For reference, the 113 build includes ported heads and a SE 58mm TB with 5.3 injectors.

What I'm trying to compare is a 2009 OEM headpipe that's been ceramic coated vs a Fullsac DX, paired with Rinehart mufflers (4" body, 2.25" cores). Key to mention is mine is a never-came-with-a-cat OEM pipe, not one that has had the cat removed, so a 2011+ de-catted header with possible cross-talk issues does not compare to what I have.

I'd love to see a dyno comparison, but I don't think any exist. Frankly, I've run both, and there is no seat of the pants difference. In fact, after my last cam change and a switch from my OEM to the DX, I actually got a new low end torque dip. Maybe that was the combo of parts, but I wonder...

The OEM merge collector chamber (or whatever you want to call it) is not small or restrictive looking, and in fact looks bigger than 2 small pipes crossing in an "X" pattern.

I suspect that Fullsac and Fuel Moto headpipes are really meant to benefit those with the 2011+ OEM headers, because removing the cat from those can cause the cross-talk issues, and it turns it into a pipe that is not used as designed. The 2009 OEM is designed to be catless, and I seem to recall some posts years back that it actually is a good performer.

In fact, I suspect the OEM squish pipe may be beneficial, as it makes the pipe perform a bit more like a 2-1 by restricting the flow to the left side. Most say HD did that for clearance reason, but again, I wonder. What I do know is that older posts by Fullsac said there is no difference with the squish pipe vs the full size cross under, and that it was only created due to customer demand.

Steve from Fullsac should be the one guy that would have some dyno charts to compare the two?

My end goal in all of this is to justify selling the DX pipe for a good buck (locally in Cdn $ especially), and run my OEM that I spent $250 getting ceramic coated awhile back, all with little or no detriment.

And if the 2009 OEM is proven to be a bit more restrictive, I wonder if that would actually equalize the fact that my Rineharts are a little too wide open, and make the OEM/Rinehart similar in flow to a DX/Fullsac 2" cored muffler (which I actually own, but don't want to run).

Long winded post, so thanks for reading, and let's see some hard facts on paper!

I'll share a little info. You need to view the exhaust as a whole from exhaust port to muffler tip.
The Non cat OEM pipe works best with 2.0-2.25 baffles. It has a restricted left side exit.
The DX Pipe works best with 1.75-2.0 baffles. It flows pretty close to equal out both sides.
You want real dyno results that mean something? You have to optimize both headpipe designs with the mufflers that work best. And then understand, the peak numbers on the dyno chart mean the least. Everything below 3K is what matters on the street. I attached a dyno chart from a back to back test on a 107. As you will see, the peak numbers are virtually identical. Yet at 2250 RPM there was a 20 FT pound of TQ difference. The seat of the pants was night and day. The mufflers that sucked are the ones your running. My point is those mufflers are OK on a stock non cat headpipe but they will kill the bottom on my DX. You have to look at the whole cocktail of parts. If your just chasing peak numbers on a piece of paper, the Non Cat OEM may look OK. When we look at the whole TQ curve, the DX with "our" mufflers will stomp it.

SG

[GregKhougaz]

I'll share a little info.... the Non Cat OEM may look OK. When we look at the whole TQ curve, the DX with "our" mufflers will stomp it.

SG

Nice, Steve.      "And thus endeth the lesson."   

[CVODON]

I love it when a question is asked, then answered with fact. Good job Steve.

[hrdtail78]

Another thing that needs to be considered in back to back testing is the cam.  The test might not show you as much with a stock cam, or close to stock as it will with a cam that has some exhaust duration and overlap.

IE A stock cam isn't going to take advantage of the shared portion of the exhaust for scavenge as a S&S 570 might.  Exhaust choice becomes more critical the further you get away from stock.

I haven't been impressed with RH's either.

[Toneaero]

So if im reading Steve's response right, the 2.0" baffles and his DX head pipe will yield the best performance.  I was originally leaning towards the 2.5" and the DX pipe.  So im guessing that the 2.5" will give more noise, but not much better if not slightly worse in performance. 

[Dan_Lockwood]

So if im reading Steve's response right, the 2.0" baffles and his DX head pipe will yield the best performance.  I was originally leaning towards the 2.5" and the DX pipe.  So im guessing that the 2.5" will give more noise, but not much better if not slightly worse in performance.

I'll share quickly.

I have an '09 SERG with de-catted stock header pipe, TTS Master Tune purchased from Fullsac and I "had" their 2" baffles in my stock 4" CVO mufflers.

It ran great with no decel pop, got 45 to 47 mpg, but the wife wanted a bit more noise.  I found a set of 2.5" baffles used and swapped them in.  To be VERY honest, my seat of the pants cannot tell the difference between the two.  I'm sure there is a hard hit in torque down low, but I've not felt it.  I've also since gone to a 30t on the trans and that did wonders to the overall performance.  But I rode with the 2.5" for a year and am very happy with the sound and they still drop down nicely at highway speeds.

That bit of wisdom will probably not help much, but it's all I can share.

[North Star]

I love it when a question is asked, then answered with fact. Good job Steve.

I agree- that's the kind of info I was looking for, and from the guy I was hoping to hear from. Posting that chart and explaining which size baffles each headpipe prefers is what I wanted to hear.

This supports what I thought- the Rineharts with the OEM did well in the past on my bike, but when I added the DX, it caused a big dip down low, since I had too much free flow at both ends which led to over-exhausting. Like Steve said, the DX is meant for smaller than a 2.25" baffle mufflers.

I do recognize that I want the torque down low, and that peak number don't mean chit. I totally agree with that, and that is what I want for my bike.

So it is now clear if I want to keep my Rineharts, I should put my OEM header back on.

One more question please Steve. How much difference if any down low would Rineharts/OEM vs Fullsac 2.0/DX make? Seems to me that each should be close in overall flow, therefore in close in performance?

[North Star]

So if im reading Steve's response right, the 2.0" baffles and his DX head pipe will yield the best performance.  I was originally leaning towards the 2.5" and the DX pipe.  So im guessing that the 2.5" will give more noise, but not much better if not slightly worse in performance.

Looks like he's saying the 2.0 works best with the DX. For my application, seeing that I'd like to run the Rineharts as long as they don't kill the low end torque, the 2.25 baffled Rineharts would be "ok" with my OEM pipe. To me, that means it would perform well, as this combo has for me in the past.

After he has shown how the 2.25 kills the low end when run with the DX, I'd hate to see how bad the 2.5 would do down low.

[Unbalanced]

One other question Steve, Jason etc, what about sensor cross talk with the cat cut out of it?  How much of an issue is that with the narrow bands and the stock collector minus the cat?

[hrdtail78]

The years running 12mm sensors.  You aren't going to have idle and parking lot speeds in closed loop.  1750/ 40kpa and up, probably OK.  Test and verify.

Cam and baffle choice is going to affect this as well.  Good news is.  The smaller baffles that are going to produce the better lower end.  Are going to help with the fresh air reversion and cross talk.

[FlaHeatWave]

In '09 only the CVOs came with cats, the others had no cats, (the OP has a stock catless, non CVO

BTW, I was told that the '09 18 mm o2s are narrow band also...

I am also curious about any potential crosstalk issues? What RPM range is crosstalk likely to occur?

[Fullsac Performance]

Crosstalk and reversion. Two completely different things that are completely related that almost always occur at the same time for same reason. Low exhaust velocity at low RPM. Reversion is exhaust gas reversing and traveling backwards in your system. It becomes a problem on an EFI engine running in closed loop when it pulls outside air in that reaches your 02 sensor and mixes with the exhaust gas around it resulting in a leaner than actual reading. The computer responds by adding fuel, the engine goes rich, power and drivability go down. Crosstalk is the 02 sensor reading the neighboring cylinders mixture or a blend of the two. This by itself is not a problem in a correctly tuned engine. If cylinder one runs at 14.5 AFR and sniffs a little of cylinder two's mixture also at 14.5, the computer does not react.  But in reality, crosstalk can not exist with out at least some amount of mild reversion. The exhaust gas from cylinder one has to travel in reverse to reach the 02 sensor from cylinder two. Symptoms of problamatic reversion and resulting crosstalk are lazy bottom end and poor low speed fuel mapping if running in closed loop. Collecting good low speed data from the stock 02 sensors while tuning is a real problem if these conditions exist. A good tuner can deal with it, but it can be frustrating. Avoiding all this is easy. Remember what your father told you. Stay away from loose mufflers with big holes. Run headpipes with 02 sensors moved as far upstream as possible. The stock non cat 09 headpipe with the 18mm sensors just below the port has no issues. Remove the cat from a 2010 and later headpipe and leave the open plenum just behind the 02 sensors, you better have some real tight mufflers and a tuner that understands whats going on. The term crosstalk gets thrown around all the time when the real culprit is reversion caused by big tubing and low airspeed.

Steve@fullsac.com

[FlaHeatWave]

Thanks Steve for clarifying

[hrdtail78]

It can be a head scratcher talking to customers about baffle size.  Bigger is always better, right?  Take away the guys that want the HP on the right for bragging rights, but for the guys that actually understand where and how they ride.  Anyway, this is how I try and explain it to them.

If a 2-1 w/ a 2.5 baffle can support 140hp.  Why do you think you need two mufflers with 2.25 baffles in each for a 110 build shooting for 125?  Error on the side of small.  Worse case, it builds great tq and you loose 3-5 from the right.  Better closed loop sampling, less pms while tuning, and IMO a good exhaust that fits the build sounds better than a big booming can that sounds like a virago with baffles pulled.