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  1. #1

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    Free Flow Exhaust

    I'm ready to go back to my stock exhaust system with my ski. The drone is just plain annoying now. But I don't want to remove the FF if I will lose a lot of performance. I don't mind losing some acceleration, but I do'nt want to lose any top end and I do lose top end I don't want it to be more than .5mph

    With my mod list can anyone tell me how my ski would perform if I re installed the stock exhaust?

    I do plan on moving up to a C3/B1 within the next few months, would I need the FF once this upgrade is done? I don't recally seeing anyone with an upgraded SC wheel and stock exhaust.


  2. #2
    RUSH.'s Avatar
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    Quote Originally Posted by rcapone View Post
    I'm ready to go back to my stock exhaust system with my ski. The drone is just plain annoying now. But I don't want to remove the FF if I will lose a lot of performance. I don't mind losing some acceleration, but I do'nt want to lose any top end and I do lose top end I don't want it to be more than .5mph

    With my mod list can anyone tell me how my ski would perform if I re installed the stock exhaust?

    I do plan on moving up to a C3/B1 within the next few months, would I need the FF once this upgrade is done? I don't recally seeing anyone with an upgraded SC wheel and stock exhaust.

    You should really think about going with the thru-hull. It will completely elminate the drone and still mantain the performance maybe even a little better. Simple to do and cheap.

  3. #3

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    Quote Originally Posted by RUSH. View Post
    You should really think about going with the thru-hull. It will completely elminate the drone and still mantain the performance maybe even a little better. Simple to do and cheap.

    Rush, I have to slightly disagree. I recently rode a 350hp FZR which had the Riva rear FF exhaust fitted and it was still a little droney. Admittedly it wasn't as bad as the Riva SHO FF exhaust, but it was still evident.

    Rcapone, if possible I would test ride a SHO/FZR with the rear exhaust fitted so you can hear it before drilling through the hull.

    I too am highly irritated by the drone and am investigating several options to try and overcome the problem. I am putting the standard exhaust back on and am going to research the possibility of fitting some kind of muffler which won't effect the velocity of the exhaust gases. I'm not sure if it is possible. I'll keep you informed.

  4. #4
    Site Admin Green Hulk's Avatar
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    When i switched from the free flow exhaust to the rear exhaust on my ski the drone was gone.

    The drone is caused from sound bouncing around in the pump tunnel area when using the stock exhaust exit location.

  5. #5
    SpeedJunky's Avatar
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    I wonder if you were to use some sort of acoustical foam on the inside of the tunnel where the exhaust exits?

    I would like to use the FF exhaust and not have to cut a hole in the boat for the direct out FF. I may try this when the time comes unless its been tried and has failed.

  6. #6
    It's not the destination, it's the journey!! Rip'nTear SHO's Avatar
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    Quote Originally Posted by Green Hulk View Post
    When i switched from the free flow exhaust to the rear exhaust on my ski the drone was gone.

    The drone is caused from sound bouncing around in the pump tunnel area when using the stock exhaust exit location.
    Jerry...there was a vid of ur ski from the back that sounded awesome.....it was on the thread of the guy revving his FZR to 6k+ on the trailer....haven't been able to find it but it gives a good idea what the rear exhaust sounds like....?!?!?

  7. #7
    Kelly_A's Avatar
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    I have Riva's through hull and still notice a drone but at a lower RPM range, 2-2.8k, than reported on the free flows. I'm rarely in that part of the range so it's not a huge issue for me.

    I've used commercial spray-on bed liner very successfully as a acoustic dampener for audio applications which are exposed to extreme weather or very high humidity. It works particularly well with transducers (which is, in effect, what the pipe is acting as).

    I know the pipe doesn't get hot enough to effect the integrity of the coating. There is a Line-X shop close to me, so that's what I've used.

    Once the pipe is in you could mark the areas which fit into the couplers and would need to masked off. Pull the pipe, mask and take it to a bed liner shop for coating.

  8. #8

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    Quote Originally Posted by Flyer67 View Post
    Rush, I have to slightly disagree. I recently rode a 350hp FZR which had the Riva rear FF exhaust fitted and it was still a little droney. Admittedly it wasn't as bad as the Riva SHO FF exhaust, but it was still evident.

    Rcapone, if possible I would test ride a SHO/FZR with the rear exhaust fitted so you can hear it before drilling through the hull.

    I too am highly irritated by the drone and am investigating several options to try and overcome the problem. I am putting the standard exhaust back on and am going to research the possibility of fitting some kind of muffler which won't effect the velocity of the exhaust gases. I'm not sure if it is possible. I'll keep you informed.
    This is probably a dumb question but, does any water come out from the waterbox and flow through the FF exhaust? If it does, then maybe a resonator isn't the answer?

  9. #9
    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by Flyer67 View Post
    This is probably a dumb question but, does any water come out from the waterbox and flow through the FF exhaust? If it does, then maybe a resonator isn't the answer?
    Yes, this is a wet exhaust system.

  10. #10

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    Take a look at this....

    http://www.hardin-marine.com/detail.aspx?ID=2141

    I wonder if something this would work? Cut the straight section of the Riva FF tube and fit this.

    Any thoughts?

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