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  1. #1

    04 GTX SC Advice

    Hello guys I need your recomendations on modifiyng my 04 gts sc, after 4 years of owning this boat I love it but I am tired of getting beat by stock RXTs. I just want to hang with them or beat tham by a little bit (65 to 66 mph) I was looking to buy a Riva Stage 1 kit but after reading a bunch of posts, I have doubts if it really works. Bottom line I want to install the best bang for the buck parts to make my boat go 65 to 66 mph. As a baseline my boat turns 7600 rpms at 62.8 mph in salt water in 90 degree weather.Thanks in advance for the help.

  2. #2
    Focker Foggy's Avatar
    Join Date
    Oct 2007
    Olathe KS
    IF you are still bone stock:

    A greenwheel or riva gen 2 supercharger wheel.
    Rising rate fuel pressure regulator to provide extra fuel required.
    Some sort of better air induction. Rivas 3" is fine for this level.
    12/20 Solas prop.. Pitch if need after running it a while to
    get max rpms at 7600-7640.

    Get rid of the OPAS system.. pos

    This should get you about 3 mph more. Then it gets real
    expensive to mod for more speed.. you'd be better off
    buying an RXT/GTX ltd 215 hp and mod it if you need more speed.

    You can do some exhaust mods, but don't really need it
    at this level. If you like it quiet now, then leave it alone.

  3. #3
    Thanks Foggy

    Yes my boat is bone stock, what kind of boost increase does this sc impeller provide and why the 12/20 prop, what is the diffrence to the riva 13/20R prop. can I just install the opas conpetition kit?

  4. #4
    lextoy's Avatar
    Join Date
    Jan 2007
    Brigantine, NJ
    you dont need any fuel mods for a greenwheel in an otherwise stock GTX SC.
    get a pump wedge.
    i have a 03 GTX SC
    homemade air intake 4" or equivalent
    opas removed
    160 Tstat mod
    aluminum pump
    12/20 bent a little bit
    rideplate holes filled
    greenhulk waterbox( amust have on an 03 to reduce clutter)
    currently 65 mph GPS at 7500 ish rpm
    a few minor adjustments and i think i'll be at 7600 66mph...

  5. #5
    As far as I know my boat already has a metal pump its a 04, so the riva stg 1 won't get me to 65 from what you guys are saying?

  6. #6
    jpeconsult's Avatar
    Join Date
    Jul 2007
    Pineville, LA
    Do not buy the Riva Stage I.

    Opt for the Kanaflex 4" intake over the Riva 3" and save over $100

    Opt for RE's over the cheap $20 block-ups or $100 plates.

    Get the Wedge, 12/20 or 13/20 prop (depends on who you talk to you), new wear ring, Riva intake grate, and Greenwheel.

  7. #7
    so so far the list is

    1 green wheel or riva gen 2 sc impeller
    2 power filter or equivalent
    3 solas 12/20 or 13/20 prop
    4 riva intake grate
    5 2 degree pump wedje
    6 opas removed or competiton kit
    7 ride plate holes filled

    wow it looks like a lot of mods to improve 3.2 mph

    will let you guys know what happens


  8. #8
    lextoy's Avatar
    Join Date
    Jan 2007
    Brigantine, NJ
    dont forget Tstat mod, can be done for about 20 bux
    yep its alot to get a few mph. its probalby cheeper to just sell the ski and get a 215 or 255.
    however its hard to find good condition skis in some areas, if you know your ski is well maintained, no ceramic clutch failures, sometimes its worth keeping and modding.
    for what its worth, mods on the 215 skis dont yeild more thana fe mph per mod, so its just as expensive to upgrade them...

  9. #9
    JFizzleJR's Avatar
    Join Date
    Aug 2005
    Quote Originally Posted by lextoy View Post
    for what its worth, mods on the 215 skis dont yeild more thana fe mph per mod, so its just as expensive to upgrade them...
    It's a little cheaper to mod the 215 The 17 tooth supercharger gear holds back the boost on the 185, the ECU is only around 7650 rev limit, the cast pistons are weaker than forged, the 215 comes with an intercooler instead of a restrictive flame arrestor, and the fuel pressure regulator is way to low to support modifications.

  10. #10
    started with a 03 GTX-SC, this is what I did

    replaced engine with a complete 05 RXT unit, missing ecu and engine wire harness $2400

    used my original wire harness off my 03 engine

    05 ecu $260

    55 psi reg $40

    knock sensor pigtail, free

    Buds hookup for reprogram, $35

    4' heater hose, $15

    couple hose clamps $10

    Will be pulling the second waterbox

    7800 rpm's at 70mph currently

    I'm hoping I will do 8000+ rpm's once I remove my second water box and do 72mph

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