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  1. #1

    Rxtx 255 to 300+ Conversion

    Okay letís talk 300 conversion. I have had an 08 RXT-X 255 since new. I love the way the ski rides and handles. It has ~270 hours.

    I am looking into the full 300 conversion kit (~$1600). Is this all I would need to run the new XXX supercharger?

    Would I need tuning or anything else? I understand the added acceleration Iíd see, but what mph would I see?

    What if I added the Stage 1 kit from Greenhulk? MPH guesstimate?

    What is the next step up from there with regards to the Supercharger, tuning, hard parts, and pure speed parts?

  2. #2
    tiderider's Avatar
    Join Date
    Oct 2018
    Or go with an ET137 and a tune for reliability. You may want to refresh the engine with a rebuild at this point..

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  4. #3
    Quote Originally Posted by tiderider View Post
    Or go with an ET137 and a tune for reliability. You may want to refresh the engine with a rebuild at this point..
    The engine is fine. Iíll rebuild it when it is needed. What is the advantage of the ET137 over the xxx charger?

  5. #4
    ptscon's Avatar
    Join Date
    Jul 2013
    300 XXX charger is big, you have to have a bit of an idea what you're doing or you might blow things up. Worst part is you'll be restricted to high octane gas or even race gas.

    Do the 300 conversion but get the smaller ET135 wheel (XX). It's a direct swap with the stock 300 wheel, no need to have the housing machined like the 142 requires.

    ET135 has about 3 psi more boost than ET137.

  6. #5
    RiverRat71's Avatar
    Join Date
    Apr 2016
    Flint River, GA
    As much as I love my 08 T-X I don't consider it a good candidate for a setup that puts you close to 80 or over. Prone to tunnel cracking or worse & stuffing at speeds near or slightly over 80. Some say 82 but I say who wants to find out. See the mods in my signature. Gets you close to 75 with factory charger & hole shot is awesome. Even with the ET137 you are going to be knocking on the door of trouble w/o prv's. I'm with Tide on doing the refresh now. If nothing else you should replace the flywheel bolts. RR

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