Quote:

Originally Posted by Holster Maker

TUCCI is "in the know"...amen brother, you and I know!

Hallelujah brother, preach on. This whole CAT removal thing is very controversial. Personally I could care less because no matter what you do to the OEM pipe, it will not flow as well as an aftermarket pipe, the smooth flowing radiused primaries and collector design just aren't there with the OEM pipe. I identified this design shortfall when I first entertained decatting an OEM system, and ultimately I went with an aftermarket header. The main reason to remove the cat is to mitigate the heat that radiates from the CAT chamber onto the rider. There is no evidence that CAT removal improves exhaust flow, but it does make the system louder and it likely interferes with the O2 sensors properly reading their dedicated cylinders. Not sure what it is you think you are "in the know" about, other than your placebo effect power gains on the butt dyno. Just because you ran into some resistance or difficulty removing the catalyst, that was never designed to be removed, and it appears like it must be a restriction, that doesn't prove the catalyst is a flow restriction. I choose to believe in measurable, quantifiable, and justifiable data that is based on some type of science, and not just I think I know.

This quote is from another forum, by Full Sac Performance, you know the guys that manufacture headers and probably know what they are talking about.

"I removed the cat and did a back to back dyno test on an 09 after AC and pipes were installed. 77 HP before, 77 after. Zero gain at this power level. I would venture to bet, at about 90 HP the cat would be holding back some power. The CVO guys report about a 5 HP gain after removing the cat on the 110". The make about 90- 95 hp with muflers and cat removed.

SG"

In this real world, dyno measured example without the CAT, by a reputable source, there is no improvement in power performance, which in an exhaust system suggests there is also no improvement in flow by removing the CAT from the exhaust system, interpret it however you want, but don’t just arbitrarily claim B.S. without some type of evidence to support it.

 

okay fabrik8r youve got my attention as someone who has actually researched the cat business, so...maybe my last question on the subject, was looking at replacing the stock pipes with Vance and Hines mainly to help get rid of some of the heat (2010 Ultra Limited), and maybe add a little more rumble. I have the stage 1, and Vance and Hines "EPA" approved slip ons. Whats going to happen with the 02 sensor? Pretty sure I'll have to have it re-mapped, but how will this affect the sensors? Anything to worry about?

Thanks

 

About any aftermarket pipe will flow better than the OEM. If your looking at a complete system, the new headers will have much longer primaries that will make up the additional length of the OEM catalyst chamber, so the O2 sensors will be completely segregated in the individual tubes, well upstream of the collector. Far as the O2 sensors go there won't be any issue with reversion or errant reading. If your goal is heat reduction, get something ceramic coated, its well worth the money, just stay away from Swain Tech.

 

I just did my RGC 103". Put Jackpot slip-ons on first. Sounded better no real performance gain. Had a set of V&H power-chamber headers from my '09. Did a SE A/C, plugged the o2 sensors in the headers, and put on my PCV from FM. Totally different bike. First I thought the slip-ons were too quiet...not now. The cat sure chokes it all off. Way more bark and way less heat. If I had know the gains by changing out the stock head pipes I might have just done that. Just my 2 cents.

 

No doubt your aftermarket header flows better. I really can't talk about the OEM 2:1:2 pipe cause I never got to interrogate one closely, but I'll assume it is similar to the 2:1. I do have the OEM 2:1 and the choke point is in the collector, not the cat. The outlet of the collector is just few thousandths shy of 1/8" smaller ID than each individual primary tube, so that is two 1 5/8" ID primary tubes merging into one 1 1/2" ID outlet. Don't seem like much but the simple math is about a 10% restriction compared to one of the primaries, and that doesn't account for the fact that you got 2 primarries merging into the one smallet outlet. Look at any aftermarket 2:1 system they all use a merge collector with about a 2 1/2" outlet. I shared this observation with FM and about 6 months later they announced a new 2:1 with a 65mm collecter, granted they haven't produced a single one yet for sale, they definately recognized the chokepoint and planned to correct it.

 

Well with all this talk of being restrictive and the choke point and not flowing better and blah, blah, blah all I can say is the heat issue is noticeably better without the CAT. Stock mufflers sound real good without the CAT too. So if it's performance then I guess go with the genius and pay $450 for an aftermarket head pipe. If it's the heat issue you are trying to resolve and get a little more rumble, then save yourself $450 and gut the CAT. Also I'm not sure how the collector can be a choke point on the 2 into1 into 2 because the head pipes are inside the collector so the outside diameter of the collector has to be bigger.

 

OK guys I did 200 miles today with the padding removed completely from the Rush 2.5". The sound was way better and no notice in performance (not that I expected any). Tomorrow I will remove baffle completely and go for a short run to work. Mainly wanting to see if I can still hear the stereo, today was no problem with the tunes. I am planning on the cat removal but still unsure of it or replacement head pipes. I have some great sound clips but can't get them to upload...??? I would love for you guys to hear them.

Tim