Winter is upon us and the bike is on the stand. I just bought a tuner and didnt really notice a difference. Im pondering all my options. Will gutting the cat and running autotune (I dont think there is a gutted cat map) yield any seat of the pants benefit? All I read is 'lower leg temp, no driving improvement.....'

 

Well....

What tuner did you buy? Watch out, the senior riders will jump in and make this a tuner vs dyno tune thread.

So I'll start. I have a 2017 Electra glide 107. Had stock headpipe and stock exhaust.
Step one change stock mufflers to upgraded slip-ons. Felt improvement.
Got the V&H FP3. Got a stock map from V&H and felt improvement.
De-catted the headpipe. Felt improvement and less heat. Better sound which if nothing else was better.
Got another map from V&H for decat and felt improvement.

V&H customer support is GREAT !

I suggest doing it, for less heat, better sound.

 

I had a Stage I, 2012 Ultra Limited; SE air cleaner, OEM header, SE Slip-on mufflers, and an HD Stage I map.

I was researching what I would have to do if; 1) I just removed the CAT from the OEM header. ...OR... 2) I added an aftermarket 2-1-2 header.

I had two reputable shops tell me that the CATs flow better than most people realize.

Both said if I just removed the CATs from the OEM exhaust, I could run an autotune with my PowerVision tuner, but it probably wouldn't be needed, nor would I feel much of a performance difference, if at all.

They also both said if I replaced the OEM header with a catless aftermarket header (I was considering a Fuelmoto 2-1-2 or a D&D 2-1-2 header) and kept my SE Slip-on mufflers, a different tune would be beneficial, but I wouldn't feel any dramatic performance difference.

Although I may be a little off on the details of their advice (it's all from memory), I remember being really shocked that both said the tune would be very close, if not the same, with a de-catted OEM header, and only a slight change with the newer header in a Stage I mod.

They said the main difference by losing the CAT would be a little bit of increased sound and a big loss of heat, especially near the passenger's right foot. The redesigned header would help the engine breathe and run a bit better, but wouldn't make a big difference in performance.

That was my education that the CAT, although it looks like a big plug in the header, really flows a lot better than I thought.

Since then, I have read numerous comments supporting those points of view and have pretty much accepted that, all other things being equal, removing the CAT will reduce heat, slightly increase sound, but offer very little performance upgrade.

I ended up going with the FuelMoto 2-1-2 header, and a new tune from them for my mods. The bike ran great, but ran great before, just hot. I compared the tune I had to the new tune in WinPV and the VE tables were almost identical.

Just my FWIW anecdotal experience...

 

Catalytic converters got a reputation for killing exhaust flow because of the GM pellet design from long ago. Those did kill flow.

But the honeycomb type flowed very well, and has long been the standard design of catalytic converters. None the less, the reputation of catalytic converters killing flow continues.

That said, yes, they do reduce flow. Only a tiny bit, but it's there. So at the far fringe level, where your butt dyno can't feel the difference, removing a cat can increase exhaust flow, and increase power. Both quite slightly.

Now of course this does not apply to say a melted catalytic converter. If you have work done, especially a bad tune or such, and the catalytic converter gets overheated as a result, and melts down internally, this will kill flow. British cars with catalytic converters back in the late 1970's and early 1980's were notorious for this. It's long not been a real problem, but it can be made into one.

Something that is real with catalytic converters is heat. They generate a lot of it. Depending on where they are, this can put a lot of heat onto the rider. BMW ADV bikes with their catalytic converter tucked up under the seat can often make summer riding unpleasant, and even damage plastic body panels. My latest M8 bike, to my amazement, I do not feel heat from the catalytic converter(s).

 

Just some random bits of info here. Slightly OT.

Fuel Moto told me the temp on the outside of the M8 cat is 700 some odd degrees F, and 200 some odd degrees once decatted.

Vance and Hines told me a couple years back that Harleys can be reflashed to stock tunes as necessary (bike still in warranty) after tuning with FP3 and there would be no “footprint” left in the ECM. Fuel Moto said this is not true, and they sell FP3.

 

I doubt youll feel any real power gain in removing the cat, but you will feel a little less heat. That being said, its for sure NOT adding any power/benefit for you, so if its something you were going to do yourself meaning no money invested, only some time, I would say its a cant lose. Now I dont think I would suggest buying a replacement header just because it has not cat as there wont be much performance gain there without changing the full exhaust so $ to benefit value really aint there.

 

If you de cat it, less heat, little better sound. I didn't fell anymore power to speak off

 

Heat reduction, increased sound.

I don't know the before hp/tq number but here is the after...
2020 117, RS468 cam, stock a/c and stock decatted header, street cannons. 131 to and 111 hp.

 

I did it for the heat. My wife appreciated the effort. Just a stage 1 makes the bike feel responsive. I used 212 ceramic lined headers in addition to reduce felt heat for my wife. I believe the only reason to remove the cat is because of heat. We’re talking cruising or touring, not racing your buddies “hot” mods.

 

Theres a lot of good answers here, thanks guys. Im trying to squeeze every ounce of 'low hanging fruit' of performance with this bike, without going into a rabbit hole of inconsequential mods. It sounds like gutting the cat will not get me any gains. I just dont have the budget for a cam job right now, but I know I want more power.