Optimal Big City Thunder baffle installation

Discussion in 'Engine, Fuel and Exhaust' started by airdrie, Jul 31, 2010.

  1. airdrie

    airdrie Member

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    I'm replacing the baffles in my V&H Big Shot longs with the quiet baffles from Big City Thunder. I had to remove the heat shields to access the mounting hole which is a couple of inches from the end of the pipes. The new baffles are currently installed 3" from the end of the pipes and sound great. The autotune of the installed Thundermax ECM will correct any change required for the EFI map.

    The instructions that come with the baffles indicate that they should be installed at least 3" in from the end though 6" is the 'sweet spot'. The instructions also indicate that they can be installed in front of the original baffles that have been cut off which would put them about 11" in from the end of the pipes that would make them quieter still.

    I'd like to optimize the performance with these new baffles. Do I
    1. Leave them alone, 3" from the end of the pipes
    2. Drill new holes 6" from the end of the pipes and re-install new baffles
    3. Install in front of original baffles (cut off) about 11" in end.

    Thanks
     
  2. airdrie

    airdrie Member

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    I went with the suggestion from Big City Thunder to mount as close to the V&H Power Chamber as possible.

    The V&H Big Shots Long pipes actually taper to a slightly narrower pipe about 16" from the end so I was only able to get the Big City Thunder QBL 1994 baffles mounted 10" from the end of the pipes before they would go no further.

    I've attached some pics of the install before I put the heat shields back on. I wasn't sure what to do about the original baffle mounting hole so I wrapped the pipe in exhaust repair tape to cover it up.

    They certainly have a deeper tone and less of a piercing bark (which my ears will appreciate after long ride). Hopefully the performance is at least as good as the stock V&H baffles they replaced.
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  3. NEWHD74FAN

    NEWHD74FAN Experienced Member Retired Moderators

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    Good deal regarding your installation. As you may have guessed, exhaust tuning for performance and "best" sound is a compromise and very subjective thing. Basically you did the right thing, first remove the old baffle and install the new one by itself, the distant from the end is as they said optional.

    Since you wanted "louder but at the same time deeper" removal of the old was best (putting two baffles in series would have made for a very quiet and "stuffed" exhaust), the back pressure may affect performance as well, probably not with the results you wanted. I think you will be happy with putting new baffle in approx. the same position as the old or farther in as you did, Good job and keep us informed how you like them. If you ride two-up, your passenger will probably have some comments too...(mine does...she is VERY picky)! :D
     
  4. ultrat

    ultrat Senior Member Contributor

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    love the look of the long double barrel shotgun pipes...
     
  5. airdrie

    airdrie Member

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    Very happy with the new baffles. The sound is lower and easier on the ears at any RPM. While cruising, the wind is now the most noticeable noise. The power is till there when i twist and seems to be improvement over the stock baffles at the lower end.
     
  6. Jack Klarich

    Jack Klarich Expert Member Contributor

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    Sounds like a job well done:D