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  1. #1
    performance enthusiast AD4342's Avatar
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    sound supression box alternative

    hi guys, i bought a used gp1300r, 06 it didnt have the sound supression box and after reading your findings of getting around 30-50RPM on top end in favour of losing some acceleration I decided to put it back. I was hitting around 7150 with ppk, efi control, D-plate, Free FLow and aftermarket air filter, the rest is stock . Now with the sound supression box I gained about +30rpm (I had to slow down and i didnt have time to test it again) I saw the difference .

    what size pipe free flow should I use to give me the same effect (RPM) of back pressure as the sound supression?


  2. #2
    Hydrotoys's Avatar
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    Very good question. You should also remember that the LENGTH of a pipe will slow down the exhaust, so you could keep adding length to the pipe with a curve at the top until the rpms come up. Just an idea.

  3. #3

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    why can,t you dump some water (into free flow)and get back pressure for xtra rpm's?

    later cd

  4. #4
    performance enthusiast AD4342's Avatar
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    i thought of testing different diameters of pipe and record the max rpms, but wouldnt measuring the back pressure would give a better indication of how big should the diameter of the free flow pipe be ?!

  5. #5
    just GOT TO DO IT! great lakes gpr 1200's Avatar
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    I used pvc pipes(45 degree elbows) the same size as both rubber hoses, It turns out one has to be like schec, 60 and one 40, then you need an addaptter (spelling).to make the two 45's fit together. the addapter makes the ID go to about 2.75 inch. but it is still a smooth flow. also you don't have to cut your hoses. It just fits.
    My RPMS on my new 1390 GK was 7330 with a 14/20. you can see where I am at now. seems to work.SOUNDS TOUGH TOO....

  6. #6
    ABBOTT's Avatar
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