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So 3 weeks later I'm still waiting for the MoCo to ship the Stage 4 131ci kit for the 2020 Road Glide Limited I just bought. while I'm PATIENTLY waiting I wondered if anyone has installed the kit and what their thoughts are on the SE high flow header that comes with it? I cant find anything online discussing just the header yet... performance, sound, etc... even the dealership service guys couldn't tell me anything, as I am the first kit they will have installed...
Of course I know there's much better out there and AFTER the warranty runs out I'll be adding the Rinehart Slimline Dual header and PV2 tuner/smart tune, but unfortunately for me I just don't want to risk the warranty on a brand new untested Stage 4 model just to eek out a few extra ponies.
So in the meantime, just looking for some reading material to get an idea of what I'm in store for with the new kit.
Did you dealer give you a ship date on the kit? My ship date is March 9th as of now, has changed twice. I haven’t ridden but I have heard the 131 with the header and SE slip-ons. It sounds really good. I’m planning to run the header that comes in the kit and S&S MK-45 mufflers.
The difference is on the inside. I can’t find the post but the cat is different. It’s high flow and has a different look. Someone posted a picture of the cat.
The difference is on the inside. I cant find the post but the cat is different. Its high flow and has a different look. Someone posted a picture of the cat.
I do not know, just going off of their response, maybe the OP can reach out to FM and get a better understanding
So 3 weeks later I'm still waiting for the MoCo to ship the Stage 4 131ci kit for the 2020 Road Glide Limited I just bought. while I'm PATIENTLY waiting I wondered if anyone has installed the kit and what their thoughts are on the SE high flow header that comes with it? I cant find anything online discussing just the header yet... performance, sound, etc... even the dealership service guys couldn't tell me anything, as I am the first kit they will have installed...
Of course I know there's much better out there and AFTER the warranty runs out I'll be adding the Rinehart Slimline Dual header and PV2 tuner/smart tune, but unfortunately for me I just don't want to risk the warranty on a brand new untested Stage 4 model just to eek out a few extra ponies.
So in the meantime, just looking for some reading material to get an idea of what I'm in store for with the new kit.
The pipes are the same dimensions but the kit pipe is supposed to be less restrictive. Over the past few weeks I've put around 1000 miles on my 131 kit and am pleased with how well it runs and overall performance for an EPA compliant engine. I put the SE Street Cannons on mine and sound is decent.
There is a video on youtube where the guy compares the 2 headers. When he showed inside the header the cat looked like it was further back...closer to the crossover. Supposedly it it less restrictive and flows better. I had a decatted header on mine already so I told them don't install it when I had my 128 kit installed. I wish I would have had the option to not buy that part. But at the time the dealer had the whole kit in stock. If you buy just that header I think its $600 to $700 bucks. I'll eventually put it on Ebay and see if I get anything for it. Along with the fan assisted oil cooler that came with the kit that I already had installed on mine.
When he showed inside the header the cat looked like it was further back...closer to the crossover. Supposedly it it less restrictive and flows better. ...
The cat might not be further back, it's probably longer then in the OEM-header (DOM Version). The header that comes with the Stage 4 Kit is the OEM-Header für international Bikes (HDI).
Usually the EURO emission requirements are more restrictive then the EPA requirements. The HDI bikes have maps that are leaner then the maps for DOM Bikes, here in Europe we had cats in the bikes earlier than in the US, the OEM HDI slip ons are more restrictive than the HDI versions. etc.
My guess is, that Harley had to use a more restrictive header to still meet the EPA requirements with the bigger engine, and that is why thex use the HDI header.
If it would be an hi-flow header compared to the OEM DOM element, they would probably advertise it as "SE High Flow Extreme Headpipe" ;-) But in the catalogue it is not even mentioned….
I recently decated a DOM header and the cat went all the way to the 2 pipes that come from the cylinders….
I haven't seen the video, but i will get an DOM header from ebay and compare it to the HDI header that I allready have and give a feedback….
Last edited by alexobelix; Apr 17, 2020 at 09:39 AM.
Meanwhile I could compare an DOM header with an HDI (Euro4) header (that is also used in the SE 128/131 Stage 4 Kits):
The catalyst in both headers seemed to be of the same type (metal cat, S-/ HF-design with 400(?) cpsi (cells per square inch)).
The difference is the length. The length of the cat in the HDI (and stage 4!) header is 15,5 cm (6.1") and the length of the cat in the DOM header is approx. 12,2 cm (4.8").
As mentioned, I recently decated a HDI header (the quote "DOM" in my last post was a typo), so I know that the cat starts at the first weldseam.
For the comparison I assumed that the DOM cat starts at the weldseam also. But it might even be shorter when locking at the first post of this thread: https://www.hdforums.com/forum/milwa...394-decat.html
This means, that the cat in the HDI/Stage4 header is at least 27% longer!
I read some technical/scientific essays reg. cats and they quote that the length has a linear influence on the restriction.
This would mean that the cat in the HDI/stage4 header is at least 27% more restrictive than the cat in the OEM (DOM) header!
So with my guess that HD used the more restrictive Euro4 header to meet EPA regulations I seem to be on the right track...
Last edited by alexobelix; Apr 29, 2020 at 05:01 PM.
Thank you fort the information Alexoblelix ! Do you thing putting a 6560176 on my European Road King will increase a little bit the overall performance or all the work involved is not worth it ?
I dont want to decat because of the mandatory vehicle inspection here in Switzerland and I fear the leak of back pressure.
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Stage 4 SE Header
