Fatshots, H-D Version vs. Supertrapp version

[blackdog30]

I have read that there are significant differences between the two, from a performance standpoint. Some of that coming from another "forum". When I look at my H-D SE mufflers, they are a straight thru design with discs, and with, or with out open end caps. Maybe at the "top end" of the rpm scale? Any comments? Thanks.

[bschultz]

The only difference between the SuperTrapp FatShots and the HD SE FatShotZ, beside the logo, is the disc configuration.
The SuperTrapps are supplied with (not installed), 12 discs and a “closed” end cap, per muffler.
The SE versions are equipped with 10 discs and an “open” end cap (installed), per muffler.

We supply 12 discs per muffler simply because that amount is usually more than adequate, for tuning, to provide enough exhaust flow, on most applications. There are occasions where more are needed, an aggressive build, stroker or big inch motor MIGHT require more discs/flow.

The “open” end cap on the SE versions provides more sound and exhaust flow (= 10-12 discs).

More flow normally means more top end HP; however it could be at the expense of bottom end torque.

[blackdog30]

Thanks, kind of what I was thinking. regards, Bill

[Ken R]

2010 Ultra Limited, 103 engine, air cleaner, Cycle Rama 575 cams, and Fuel Moto Headpipes. I increased discs from the included 12 to 18 per muffler and got significant increase in torque. But there's a dip between 3,000 and 3,750 RPM. Can't seem to tune it out.

Reduced the number of discs just as an experiment, and the entire torque line dropped 3 to 4 ft lbs. (WOT pulls after tuning)

Thinking about ordering a set of open end caps just to see if maybe it improves things. Should I remove discs or just leave the 18 in each muffler.

I'm hoping open endcaps don't increase the noise appreciably.

[bschultz]

18 discs sounds excessive for your build; however if reducing the number of discs doesn't get rid of the dip then I would look at one of the other variables like ignition timing or fuel management.
Have you talked to the folks at Cycle Rama or Fuel Moto? These guys know the combinations that work, including our exhausts.

[chasrob50]

I have a stock 2011 road king and have added only XIED by nightranger to richen the AFR. I would like to add the slip on SE fatshotz but I don't want to have to do any mapping or download, and keep it exactly the way it is. Is that possible?

[bschultz]

Shouldn't be an issue as long as your fuel management system doesn't hinder and/or inhibit the functionality of the "closed loop" fuel injection.