Fatshot vs. Kerker

[baggermanmcp]

So, on an 07' w/255 cams running 10 discs should be the "sweet spot" for performance and sound with the Super Trapp Fat Shots closed cap?

Can you give me an idea on what I get, if I purchase a set of open end caps, as far as increase in volume? I used to run the 128-78020 but decided to move to the fat shots for a bit less volume and more flexibility.

Thanks for this great insider forum. Your tech. support is greatly appreciated!

[bschultz]

You will gain volume (a couple db's) approaching the Kerkers, P/N 128-78020; however a deeper sound.

[Gary D]

If I'm right, A HD fat shotz muffler with an open end cap and 10 discs will flow the same as a closed end cap and 20 discs? So if I put that fat shotz muffler on my -09- Road Glide, it would be the same as a closed end cap with 20 discs. Would it be too free flowing? I'm asking because you recommend 10 to 12 discs and a closed end cap as a starting point if I mounted supertrapp fatshots. I'm guessing a HD fat shotz muffler with an open end cap is flowing the same as a supertrapp muffler with 20 discs and a closed end cap. Please shed some light.
Thanks
Gary D.

[bschultz]

You are correct; however keep in mind the HD FatShotZ were introduced for the 2010 models to provide maximum flow/sound with a catalyst equipped headpipe.
Our testing and feedback from tuners with a mildly modified pre-2010 touring models, equipped with an OEM headpipe, found the best performance with no more than 12-14 discs (w/closed end-cap).

[Gary D]

So putting screamin eagle Fat Shotz mufflers with its open end cap and 10 discs might not be the optimum set up for a stock 09 HD touring model?
Gary D.

[bschultz]

That's correct.

[Gary D]

With those pipes (screamin eagle fat shotz) on a stock 09 HD touring model, what would be the best set up?
Thanks
Gary D

[Gary D]

TTT
Thanks again
Gary D.

[bschultz]

On an '09 non-California model (no cat), stock (no mods), we found performend best with 8-10 discs and the closed end-cap.

[gkriske]

Reading this makes me wonder if I've done the right thing with my 2008 Ultraclassic.

I've got a SE aircleaner and SERT with the HD Fatshotz. Stock other than these.

Had my bike dyno tuned and gained about 6 hp and 6 ft/lb torque.

The mufflers have a nice low rumble, just a bit louder than I expected. Not too bad, but leads me to ask:

- should I have gone with a closed end instead?
- if I put a cap on them, do I need to have it re-tuned?

Rather new to all of this, appreciate your help!