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[Schnobel]

Anyone test the difference between keeping the OEM header pipe with the cat removed verses say a Fullsac x pipe as to performance?

The guys selling the cat less OEM's claim you will get the same performance at a 1/3 the cost.

Curious if anyone has Dyno'd this to see if its true.

[ultrarider123]

Took the stock header off Skunk Ryders SESG a couple months ago and replaced with a gutted one (local guy does it for us).  He cuts a section out of the stock header, removes the catalyst material and tig welds it back together.  With the gutted header, the stock SE mufflers with the plug removed and a SERT, he was out about $700 bucks.  He had it tuned and dyno'ed by a great guy at K'ville HD that has a very good reputation (or would not have used him otherwise) and he got 95 HP and 114 lb/ft of torque with a very linear curve.  Sounded great, better output and not much money.
As for other aftermarked system results, there are quite a few posts with HP and Tq results posted.  In the case of the gutted stock header, the money spend along with more power/tq along with eliminating some of the lean issues from the factory really made the most sense.  It's so much better, I may just go that route myself someday.

[Steve Cole]

One needs to be careful when gutting a stock head pipe if you plan to use the Closed Loop control functions of the ECM.

[Schnobel]

One needs to be careful when gutting a stock head pipe if you plan to use the Closed Loop control functions of the ECM.

And why is that?

[willyB]

I cut a simple batch out of one side of the header where the cat is located with a small grinding wheel. Took a chisel and hammer and knocked out the cat. I then had a local shop weld it back up for $30.

Best money I ever saved!

[Schnobel]

I cut a simple batch out of one side of the header where the cat is located with a small grinding wheel. Took a chisel and hammer and knocked out the cat. I then had a local shop weld it back up for $30.

Best money I ever saved!

Do you ever have it dyno'd before or after to see what difference it made? Really would like to know who that de cat'd pipe compares to a full aftermarket set up.

[miker]

My highly technical seat of the pants dyno showed good results after a tragic accident resulted in the cat falling out.  
I did add 1.75 full sac bafflesm nuch lighter than oems..bikes has run fine the last 10k...o2 sensors look fine...I check those versus plugs nowadays to look for combustion happiness...I had removed a D&D fatcat..burned my leg too much and was getting too loud on my ears..performed well though.

[willyB]

Do you ever have it dyno'd before or after to see what difference it made? Really would like to know who that de cat'd pipe compares to a full aftermarket set up.

Before installing the Decatted header I had been running true duals with V&H Hi Outputs. I had it dynoed and it was 89HP and 108TQ. I was STUPID LOUD!

After getting tired of my ears ringing I decided to see what would happen if I installed the Decatted header. The result:

** it was significantly quieter
** With the true duals the bike seemed to rev quicker but with the Decatted header the bike definitely has a more torquey feel.

Before the bike didn't have that school bus cam feel you read about on the 255 cam. After, you can really feel where that cam works.

Personally, I love this setup!

[ultrarider123]

Do you ever have it dyno'd before or after to see what difference it made? Really would like to know who that de cat'd pipe compares to a full aftermarket set up.

Forgot to put that in my other post....before installing the de-catted header but with the de-plugged SE muffler (so pretty much stock), the dyno run showed 87 HP and 100 lb/ft of torque.  After empty header, SERT de-plugged muffler was 95 and 114 respectively.

[Schnobel]

My highly technical seat of the pants dyno showed good results after a tragic accident resulted in the cat falling out.  
I did add 1.75 full sac bafflesm nuch lighter than oems..bikes has run fine the last 10k...o2 sensors look fine...I check those versus plugs nowadays to look for combustion happiness...I had removed a D&D fatcat..burned my leg too much and was getting too loud on my ears..performed well though.

So after the unfortunate accident which took out your cat, did you retune the bike or just added the Fullsac baffles? Would be interesting to know if the OEM map could handle the catless rebaffled bike without any problems like running lean, etc.

[miker]

No, I just let the o2 sensors and the ecm do their thing...taking a peek at the sensors at a thousand miles for a reason to screw with the fuel tables but I am either too lazy or not anal enough...I've been around the block awhile with this stuff.  The bike runs fine...

After crawling through a brazillion tuning tables I found the one I had in this bike with the D&D fat cat and oem cams (duh, huge pipe tiny cams )  the dyno tune in it was not to far off the oem anyways...oem cams are still in there so going nuts with dyno time is not high on my money spending list..

[Doc 1]

And why is that?

Because the 02 sensors will cross talk effecting the way the bike runs in the lower rpm ranges.
Doc

[Schnobel]

Because the 02 sensors will cross talk effecting the way the bike runs in the lower rpm ranges.
Doc

So Doc,  what have you seen in regard to my post? Is there any significant difference between the OEM headers without a cat verses an aftermarket header and do you think you still need a remap if you just lose the cat and change from the stock baffles to the Fullsac performance ones?

Thanks

[North Star]

Do you ever have it dyno'd before or after to see what difference it made? Really would like to know who that de cat'd pipe compares to a full aftermarket set up.

I'll have that answer for you by the end of the month. I'm running a Fullsac "B" x-pipe, and just had some engine work done. My builder said I'm down about 20 tq between 1500-2500 rpms, and that I would be much better off with the de-catted OEM headpipe. So, I pick one up used and am going to have it ceramic coated. Then, I'm taking it back to him for a touch up re-tune and dyno run, and we can compare that run against the runs he did a couple weeks back with my Fullsac on.

He says the Fullsac shines in higher rpm HP, but the larger collector of the stock pipe is better for low end torque. Some may want to debate this, but the torque curves willl tell the real story. We will see.

[Steve Cole]

Your going to need to dyno with all the engine work done now with the Fullsac if you want to get real comparable results. An old dyno sheet (before engine work) with work done in between isn't going to be any good for a real comparison.