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  1. #1
    64physhy's Avatar
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    Free Flow Exhaust Idea

    I've been looking at the various free flow exhaust options out there, and it just seems that some, like the R&D, are so simple, it's hard to justify the price.
    So I measured the water box outlet at 3.25", which is a fairly hard to find diameter aluminum elbow, so here's what I've come up with:

    This elbow, which will probably need the long end cut a little.
    http://store.max-redline.com/servlet...l?sfs=2b2f747a

    With this coupler.
    http://www.frozenboost.com/product_i...b3f51bd0847302

    The elbow would come off the waterbox, held on with the coupler above. The stock hose that goes from the big sound deadener to the outlet gets turned to where it will mate up with the elbow, similar to the R&D system.

    Total cost (minus tax and shipping): right about $45 with the T-bolt clamps (not listed above). (R&D wants $190 for an elbow to do the same thing)

    Has anyone tried anything similar? I'm staying away from the PVC pipe route...not bashing anyone who's done it, just not for me.


  2. #2
    64physhy's Avatar
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    Another option I found is using a silicone elbow, which is fairly easy to find, and an aluminum coupler, but I don't know about the heat with the silicone. I guess if the stock rubber and plastic components can take it, the silicone should be able to.

    http://www.votionspeed.com/servlet/t...0-Elbow/Detail

  3. #3
    64physhy's Avatar
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    Has anyone tried it? Would using the silicone elbow instead of aluminum work, or will the exhaust gasses break it down?

  4. #4
    mjh3ides's Avatar
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    Silicone will work fine as long as it's high temp hose. I used the R-rated kit for 150+ hrs which uses that type of hose before switching to the rear exhaust.
    http://www.rratedperformance.com/NEWFOR2008.html
    A quick search turned up these parts to replicate their kit for ~$80 before buying clamps. Looks like the aluminum elbow would need to be cut to size though.
    http://www.atpturbo.com/mm5/merchant...Code=SIL-135EL
    http://intakehoses.com/Merchant2/mer...gory_Code=MIE0

  5. #5
    64physhy's Avatar
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    Quote Originally Posted by mjh3ides View Post
    Silicone will work fine as long as it's high temp hose. I used the R-rated kit for 150+ hrs which uses that type of hose before switching to the rear exhaust.
    http://www.rratedperformance.com/NEWFOR2008.html
    A quick search turned up these parts to replicate their kit for ~$80 before buying clamps. Looks like the aluminum elbow would need to be cut to size though.
    http://www.atpturbo.com/mm5/merchant...Code=SIL-135EL
    http://intakehoses.com/Merchant2/mer...gory_Code=MIE0
    I saw that R-Rated kit too. It's actually the most reasonably priced. I see them new on ebay for $139. So the tubing is 3.5? I measured it closer to 3.25. Another reason I left that one alone is the 135 degree bend, but it's not looking like what I had in mind is going to work because I thought that once I repositioned the exhaust tube by rotating it a couple bolt holes, it would be higher than it is.

  6. #6
    mjh3ides's Avatar
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    You may be right that it's 3.25". I don't have the ski here to measure & thought I remembered it being 3.5". The 135* bend might become restrictive in a higher HP boat, but I didn't notice any increase in performance going from the R-rated to the Riva rear exhaust. There were two reasons I preferred that design over other FF's on the market: It had a deeper throatier sound than the Riva kit that uses a long aluminum tube, & it was fully supported by the foam rubber block that was there for the stock resonator. I've seen one or two people have the OEM rubber exhaust outlet tube rip from supporting the weight of other kits, & that was a concern for me because I ride offshore a lot.

    IMO, the best way to go for a mild modded ski is Tommy Jordan's mod to the OEM setup. The FF designs all have the annoying drone at 3-5K rpm, & the rear exhaust eliminates the drone but is annoyingly load at speeds <40mph.

  7. #7
    64physhy's Avatar
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    I rarely ride in the "drone range." I mostly ride in the ocean, and don't have to ride in no wake zones much. I'm normally in the 5-6000 range. I already have Tommy Jordan's mod done, except I left the small resonator box in. I'm trying to get a little more aggressive sound.

    I finally found a thread after about the fourth time of searching and found where somebody pretty much replicated the R-Rated system. They said they used 3.5", so I guess I'll go with that. 3.25" is closer, but it would be a pain to try to stretch it over. (It's really closer 3.4", but since it's metric, won't get an exact fit unless it comes from Japan)

  8. #8
    64physhy's Avatar
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    I got this pipe http://store.max-redline.com/servlet...Pipe-90/Detail
    It showed up yesterday. The walls on this thing are thick, 3mm, which is just under 1/8". Very solid piece.
    I thought I would have to cut it, but i was able to slide the OEM outlet tube over it far enough (about 6"). In order to work with it, I took the outlet tube off completely. I'll get some pics this afternoon. I ordered a 135 degree silicone elbow also, but it's coming from a different place and should be here tomorrow.
    Since I had to order the parts from two different places, I ended up spending a total of about $22 in shipping, so I'm in a total of about $90-$95 on this set up. I did find the aluminum tubing for cheaper elsewhere, but it was thinner walled and didn't have the flanges.
    Click image for larger version. 

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  9. #9
    64physhy's Avatar
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    Ok, so i finished it. I ended up having to cut 4" off one end of the elbow and 2" off the other end. The 2" was on the end from the waterbox, the 4" on the end to the exit tube. I also had to do a little trimming to the 135* elbow. I had to mock it up several times until I got it all lined up right with the trimming and the angle on the elbow tube. It would probably be worth it to most to just go with the R-rated system, considering it's only about $45-50 more, and should bolt right in with no test fitting. Sorry, I forgot to get pics while i was finishing up.

  10. #10
    What I did on my GP1300R was take the big black pipe and box out and on the cast pipe where the exhaust exits the ski there was I 90 degree bend I angled it so it was facing straight toward the hole in the water box and got some 90mm stainless thin wall alloy cut to around 10 inches. Then got some 100mm thick wall stainless and cut a 2 inch strip off. And then slip the 100mm over the 90mm so it sits flush with the end and weld it all the way around the seem.

    And the 90mm will fit into the exhaust exit end and the 100mm goes to the water box and I cut the end off the big black pipe that was originally connected to the water box to join it and used all original clamps to secure it back down. And it worked a treat and sounds awesome

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