Yes I've noticed forsure. While my headpipe is decatted and the bike has the SE8 447 TQ cam in it. The low end prefers the stock mufflers. Once I get the valve train rattle figured out. The stock mufflers will probably go back on. And the Eliminator 400's on to somebody else. When the baffles blew out of the Eliminator 400's a few months ago the bike fell flat on it's face. TQ and HP were gone. Proved to me the M8 has to have some back pressure. Was very clear.

But I would think the Street Canons would help with back pressure compared to my Eliminators 400's. No packing in them at all.

 

I think the Street Canons work great for torque, I picked up a nice gain down low over just the SEPST SE Stage 1 ecm calibration having them dyno tune with the SEPST...runs great in the 2000-4000 rpm range..I din't get a stock dyno run but it would be below the red Stage 1 ecm calibration

 

I played a little with different combos all butt dynoed !

#1 Arlen ness big sucker and powervision stock improved map.
This still had the bottom end torque of a stock setup. 2 up torque/power very good

#2 Added CVO mufflers with the Fullsac 2.25 Baffles/techmat, Autotuned powervision map
Bottom end suffered a good bit. Did'nt feel the choking off of the stock mufflers in the mid to upper end. Exhaust note louder, not impressed.

#3 Decatted stock headpipe with the Fullsac 2.25 Baffles/techmat.
No performance change from #2. Deeper exhaust note. Pops when accelerating letting off the gas sometimes (this sucks).

#4 Decatted stock headpipe with the Fullsac 1.75 Baffles/techmat.
Regained some bottom end. Still popped. Exhaust note better then stock. But still don't sound like a Harley

#5 Decatted stock headpipe with the stock mufflers.
Back to the bottom end torque of a stock setup. 2 up torque/power very good. Still pops once in a while.
Actually like the quiet of this setup. 2 up riding more enjoyable.

Like the #5 setup the best. Heat is gone from the decat. Never could dial out the gear shift exhaust pop once in a while. But being careful about the shift points I could stop it. I think taking the cat out of the head pipe with a stock setup is not the best idea. Exhaust is probably too free flowing. 28,000 miles on the bike now.

S&S 365C cam and other goodies on the shelf for winter work. And I'll either put the stock headpipe on with cat. Or most likely pickup the fullsac headpipe.

 

Exhaust scavenging, turbulence, and velocity effect torque. So does an inadequate tune.
I have had different size mufflers on all kinds of older and new Harleys, and most new bikes with V & H. I have never heard of anyone "blowing their baffles out "if installed properly. I'm sure V & H would replace them.
I'm running the V & H Eliminator 400's currently. Had a good dyno tune with a TTS tuner and have 142 torque.

 

 

correct..doesn't the Ultra twin cooled have higher compression..perhaps your perception is reality with the 'butt ometer' because of that

 

My bike will be delivered to my home Tuesday after the short block install under warranty and the Stage I with 2 into 1 street cannon, high flow AC and SEPST Dyno tune. Dealer rep assured me that the bike was transformed from its previous state and that it posted some impressive dyno numbers. Also said it now idles at 950 warm and is smooth with no more counter balancer scissor gear screeching at idle. They also assured me that the dyno sheet would be sent along with the bike delivery. I remain optimistic and at least for now my confidence has been restored. I hope I like it as much as the dealer manager assured me I would. I'll try and post up the dyno sheet results once I get it. Not my hometown dealer mind you as I had to travel some 150 miles to find a reputable one that would acknowledge my issue with no BS. I hope I'm one of the happy guys after all is said and done as I plan many outings on this puppy with my wife in tow.

 

What is a 2 into 1 street cannon?

 

2018 Road King stock has good low RPM torque. I added V&H Twin Slash ovals with no other changes and noticed I lost some low end torque. Will a proper tune correct this? I am waiting for warrantee to expire before I do anything else.