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Thread: Sound Adjustment Fat Shots

  1. #1
    ocezam Guest

    Default Sound Adjustment Fat Shots

    I've got an '08 FLHTP "Cop Glide" with 103". S&S air cleaner. Rush ceramic coated True Duals. XIED's.

    I just purchased a set of Fat Shots with 24 disks per side w/ closed caps. Tried installing w/ 18 disks but bolts were too long so I installed all 24 disks on each side. These mufflers have a great tone, very deep! Even with all those disks the performance is better at all RPM's (seat of the pants dyno) than my much louder 4" Cobra Slip On's.

    My question is how to get more sound out of them. From reading here, I'm guessing the advice would be to add open caps and 10 less disks per side. Would this change the tone of the pipes? How much louder would it be? And I guess I'll need shorter bolts. Kind of a bummer 'cause I like the closed cap look.

    Adding disks to the 24 per side won't do much for the sound I'm guessing?

    Thanks in advance!

  2. #2
    Join Date
    Sep 2010


    when the discs are stacked, the gasses have to pass through a "w" shaped passage, this breaks up the sound waves, particularly the higher frequencies, leaving the low tone that you like.

    so, supertrapps flow more exhaust at lower sound levels- if your configuration

    if you put on open end caps ( the cone shaped 'closed course' ) they are equivalent to about 10 discs in terms of tuning the flow.
    and you'll get more sound out of them.

    the machine screws are not anything special, hardware store will have in all lengths- put anti seize on them.

    you may find that with open end caps ( and cat in place) 3 discs a side might be about right for performance

    your header pipes are not great for torque, I don't know if a lower disc number may help restore that or not

    mike ( not an expert but i use supertrapps alot on a bunch of bikes)

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