Finished the straight 2" pipe to replace the 2" louvered baffle, ended up cutting the inside portion to the same length as the stock S&S dB reducer, the visible rear part is 1-3/8" longer.
I did a couple of auto-tunes today, the off line performance is better, mid range performance is close but probably missing a bit of the very top end of the RPM's compared to the louvered insert. It's a lot quieter but not as quiet as the S&S insert but they have to conform to EPA sound standards. The back talk when you let off the throttle is almost all gone since the exhaust note is a lot softer compared the louvered insert which sounded more like a Bassani Road Rage, so it's more police friendly.
For the driving I do, having that off line performance really makes the riding around town fun, I was out all afternoon, nice day.
Glad I did this experiment, would be interesting to see how the Super Street does with a 128" motor, but unless I was really bored this Winter this Stage II is running really well. Maybe a dyno tune this Fall.

 

Great idea and we'll documented experiment Mike. I am pretty darn close to pulling the trigger on building out a 128 set up, currently talking with a few shops. A few areas I'm discussing are whether to do heads along with a larger TB and port match and which exhaust to go along with it OR stock heads for now and maybe just the SE 55mm TB with a complimentary cam. Recently Moonshine HD posted a cam comparisons for 124/128 builds....they noted that the Thrashin AR exhaust is the' best exhaust' for softails; however, I still see the 'softail dyno dip' in their curves even with that exhaust. One other point on Moonshine video is they have some not so well known cams in the mix, one with their own branding.....so I'd take that with a grain of salt as well. In addition, the price of the Thrashin AR pipe is not necessarily high, but actually offensively high in my opinion, for a black ceramic pipe that doesn't even have heatsheids. ($1700, offensive). All the more reason Im really rooting for S&S to be a top performer with 124/128 builds.

Interesting... You can buy the Thrashin supply 'dog ball' baffles separately: https://www.thrashinsupply.com/collections/exhaust/products/ar-system-muffler-baffles?variant=29787576594

I'd really like the Superstreet to work out, especially would like to see some dyno curves for these different inserts....it would be the best pipe dollar for dollar for the Softail performance-wise if these inserts do in fact help with the 'softail dyno dip'

The only other pipe that is really catching my attention is the Thunderheader and/or Fatcat. The Thunderheader is backordered till around October or November though.

 

I saw that Khrome Werks has a baffle like that but a lot of this stuff is out of stock.
I chose to deal with the Super Street to keep the noise down, any upgrades I do will probably be built around a quieter exhaust because of old ears.
There are so many ways to go with a big bore build. I already have the 55mm SE intake so just larger injectors with stock heads on a 128", low or higher compression depending on which cam is used, is a good start and can be upgraded down the road. My guess is a 11.5:1 128" with the right cam could shoot for a 145/145 goal on pump gas.

 

Cool experiment and good to hear of the positive results. I got my baffle in and it seems more mellow, deeper and not as raspy on idle and it definitely is a bit deeper and louder upon cracking the throttle than with the chopped stock dB reducer. It sounds more like it does without the dB reducer so we shall see if this drones my ears like the pipe did without the dB reducer.

Is that Race Only stamped on your muffler or is that computer effects? Just curios because mine doesn't have that and I would be like what the F*$@ if it did.

 

Which baffle did you get?
I bought the exhaust 3 months ago, the "race only" was printed on the muffler, probably a new EPA rule.

 

I got the same baffle that you posted the link for. The S&S touring pipe baffle. And that kida sucks that they have to print that on the race only versions now.

 

Well after autotuning again and riding for a couple of hours last night, I can confirm that the pipe performs better with this baffle installed. The tone is deeper and a bit louder when getting on it but it sounds more "smooth" now when cruising at a steady speed and throttle.

I'll run autotune a couple more times but it's running well and I'm very pleased with the bump in mid and upper range performance now. Thanks again Mike for this suggestion. It was well worth the 23 bucks spent on the baffle.

 

Can't beat that!
I noticed cruising in 3rd gear when I was at 2,400 RPM could feel the power start to build. The idle felt (sounded) more aggressive too, as if the Stage II 114" really likes this combo.
This shows you how sensitive the M8 is to a exhaust change, the right exhaust makes for more fun for sure.

Thanks,
Mike

 

That's exactly what I've been noticing. Before I could whack the throttle in first gear and it wouldn't quite break loose without clutching it. Now if I open it up it breaks the rear loose no problem.

I thought the more agressive idle lope was just in my head but I guess not. I agree this does really show how sensitive the engine and cams are to different exhausts and minor changes. This small change made a big difference.

 

dB Reducer - SAE J2825 4.5 - 2 SS | S&S Cycle

Are these 2' or 1'-7/8 OD ?