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Thread: HP Difference when removing cat on -13?

  1. #1
    Standard Member Jocke's Avatar
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    HP Difference when removing cat on -13?

    I have a HP4 with the cat still attached to the bike.
    I just did a run on a track and was reaching 97db redline in second gear.

    I searched online but cannot find any dyno readings etc with and without the cat.

    Maybe you guys can help?

    My bike is mapped and using a PCV with the cat installed. But is there any gains on changing it to a race pipe? (might also need to use the db killer if I remove the cat).

  2. #2
    Forum Admin soofsayer's Avatar
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    Re: HP Difference when removing cat on -13?

    I removed the cat on mine and it made the midrange more eager, not sure about increased hp although it probably adds a couple.

    The biggest benefit is the weight reduction as the cat is heavy. Very noticeable.

    You will need a db killer if you do remove the cat as it becomes much louder.

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    Standard Member Jocke's Avatar
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    Re: HP Difference when removing cat on -13?

    Quote Originally Posted by soofsayer View Post
    *
    Did you remap it? Was it necessary? My friend bought one and he got the exact same HP with a remap, he didnt notice any difference. But he is not using full throttle ever I think

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    Forum Admin soofsayer's Avatar
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    Re: HP Difference when removing cat on -13?

    Quote Originally Posted by Jocke View Post
    Did you remap it? Was it necessary? My friend bought one and he got the exact same HP with a remap, he didnt notice any difference. But he is not using full throttle ever I think
    Lol. I didnt get a remap but mine was stock with no pcv. Bmw said the bike would self adjust with the decat, I was happy with it. Others have had theirs remapped and said its better although I dont trust dyno tuners.

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    Forum Moderator Oli's Avatar
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    Re: HP Difference when removing cat on -13?

    A remap with a full length full system is generally not necessary so long as the stock lambda sensor is installed.
    I ran my RR with an Akrapovic Evolution system for ~ 12K miles before having a PCV installed and a custom map made.
    The attached photo shows the before and after Dyno runs of my RR with the base map followed by a full custom map (by a genuinely honest Dyno operator).

    The “low” power output is due to a) a well calibrated dyno with no BS fudging to make a higher number and b) that my bike had ~ 20 K miles on her, so was roughly 10 hp lower than the first dyno run we did when the exhaust was first installed.



    My 15 RR pre and post PCV custom map with an Akrapovic Evolution full system

  7. #6
    Standard Member Jocke's Avatar
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    Re: HP Difference when removing cat on -13?

    Quote Originally Posted by Oli View Post
    .
    Thanks for the info. Mine actually has a really nice curve so maybe I should just enjoy it and save some money.
    It just hurts to see it with that fat cat there.....

  8. #7
    Forum Admin soofsayer's Avatar
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    Re: HP Difference when removing cat on -13?

    You could always try it and if you dont like the fuelling revert and sell on the link pipe, or then get it mapped. The weight saving is significant, I think you will like it overall.

  9. #8
    Forum Moderator Oli's Avatar
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    Re: HP Difference when removing cat on -13?

    Quote Originally Posted by Jocke View Post
    Thanks for the info. Mine actually has a really nice curve so maybe I should just enjoy it and save some money.
    It just hurts to see it with that fat cat there.....
    My point entirely, there is no “need” to spend the money on a fuel module and custom map unless there is a specific reason for it as you won’t gain a significant amount.

    I do however agree with de-catting the bike as the weight saving and sound are genuinely worthwhile improvements.
    I agree with Soofsayer, try the link pipe prior to making a decision on a fuel module. I suspect you’ll be wholly satisfied and won’t bother custom mapping the bike

  10. #9
    Standard Member Jocke's Avatar
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    Re: HP Difference when removing cat on -13?

    Sounds smart.

    Trying to find one second hand but it is very hard.
    Price in Sweden is basically close to 500€ which is a bit to much currently (smarter to spend it on track days).
    Let me know if you find one cheaper.

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