If they don't change the air going out, that means they don't improve the bike's performance, and they don't make the bike louder. If that were the case, why would anybody change slip-ons?

They do change the air going out. Absolutely. What we don't know is from what slip-ons to what slip-ons, and how much does the air flow change. If the change is pretty small, then you can get by without a tune.

 

Oh I am not that good, but my guess would be that in the Trump era this will fade into nothingness.

 

Fair enough but I will bet they are damn close. Each new model has this beta period and there may not be a lot of M8 data but there is a **** ton of other introductory data they can use to get scary close.

 

I think if there is a change in air out, it must be minuscule, since the cat is left intact. I assumed shapes and sizes, and of course different baffle options had more to do with the change in sounds noticed with different slip ons. Still though, the exhaust is bottlenecked with the catalytic converter still in there. Which is why for most slip ons, they say you dont need a tune. I guess you could do one and the bike could benefit in some ways over just the stock tune, but not sure its enough to warrant a $300 tuner until you do change the air intake.

I think the SE line offers two options. Slip ons by themselves, leaving the cat in the header section, or full exhaust system where the cat is split and one in each side muffler section.

 

Apple and Samsung have lots of data on past Iphones and Galaxy Tabs too but something always goes wrong when they put out a new iteration of the models. Phones catching fire, exploding, bending, etc..can't catch that stuff in the lab or actuarial prediction because that stuff can be caught only after thousands of people do real-world beta testing on the new model. Until then, it's all an educated guess that the new device will hold up.

 

Unless the new slip-on and internal baffles results in the exact same back-pressure, the flow will change. It may be small enough to not be of concern or cause any issues with the engine, but the change is still there. You just modded a stock configuration and changed flow rates etc etc...Extremely petty and trivial but it doesn't matter to HD apparently. As other poster already pointed out, there are now warning labels for even the Street Cannon mufflers-[-use of this part requires ECM recalibration.]

 

Are the Screaming eagle mufflers even worth it though? They've never been much louder then stock in the past I don't see it being any different for the new M8.

 

I've really grown to like and appreciate the performance and sound of my Street Canons..yes they are quiet at idle but once opened up they have a racy tone and cool sounding deceleration growl..and when you're cruising during Touring they are easy to live with and enjoy, no annoying drone..glad i got them, much better than stock which weren't altogether bad at all

 

I guess ill have to hear them in person. If they sound good I have no problem going with them. Hell id rather everything on my bike to be from Harley.

 

I think you need to separate loudness and quality when it comes to exhaust sound. It's all subjective but IMO I have noticed that people too often equate loudness with quality when it comes to exhaust and use that as the sole criteria for selection. Loud=good sound quality. Quiet=poor sound quality. If you take a few Lady gaga songs and play them on your stereo, it's going to sound like sh*t no matter how loud or soft you crank the volume. People will be annoyed and even your dog will run for cover.

IMO the Se Street Cannon's I have heard are not a whole lot louder than stock but the tone is more aggressive and baritone and sounds more meaty. The same for a pair like the S&S MK45 which I just got. Very muscular sound but not overbearing. You feel a thump thump thump more than you hear an annoying brappppppp. It's all subjective but for me, it is good quality sound. If someone just wants a super loud ear splitter that has no texture whatsoever and is basically just a noise maker, they might as well just drill out the stock baffles and remove the cats and save money.