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  1. #1
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    HPF 2.5 Open Dump?

    i hate the exhaust note the flex section makes off the dumptube. i actually replaced the flex section (aka teh chinese fingertrap) a while back when i was hunting down exhaust leaks on the downpipe so its brand new and should be the most quiet i can make this dumptube. the cars fully buttoned up now, and very very quiet for the amount of power it puts down but the flex section sounds like a$$ when the cars bogged down.
    my questions to you hpf guys running open dump stage 2.5 and down....
    this first one might sound stupid but...
    open dump won't increase exhaust note, just blow off as it is now 'open' and no longer recirc'd, yes?

    and now that you switched to open dump have any other unfavorable exhaust notes come forward? i guess that questions directed towards those who don't have an ungodly loud exhaust and can actually hear $#@! other than their tail pipes!

    also how long did the retune take from HPF, and how much $?
    performance gains, if any?

    thanks.

  2. #2
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    Was yours the updated version?

    Click here to enlarge

  3. #3
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    dumptube? Why not install a 3inch cutout?
    Click here to enlargeClick here to enlarge

  4. #4
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    yes, its the updated ribbed design. but it sounds only slightly better than my old beat up one. theres alot of air that passes through that weave at just idle :/

  5. #5
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    Click here to enlarge Originally Posted by dreikraft Click here to enlarge
    also how long did the retune take from HPF, and how much $?
    performance gains, if any?
    Bump for these questions.

    Stage 2 or 2.5 E9X M3 S65 V8 supercharger kit for sale
    : http://www.boostaddict.com/showthrea...r-kit-for-sale

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    You'll gain about 20-40wtq and about = hp I did on my s4 with a open dump

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    Click here to enlarge Originally Posted by 600whp S4 Click here to enlarge
    You'll gain about 20-40wtq and about = hp I did on my s4 with a open dump
    what about decibel gains exhaustwise?

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    I run a 4" ribbed flex section and no exhaust comes out at idle.... that's not good. They're flexible exhaust sections, its unsafe for exhaust to come out - its coming into your cabin. Contact them for a replacement.


  9. #9
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    Click here to enlarge Originally Posted by 5mall5nail5 Click here to enlarge
    I run a 4" ribbed flex section and no exhaust comes out at idle.... that's not good. They're flexible exhaust sections, its unsafe for exhaust to come out - its coming into your cabin. Contact them for a replacement.
    as soon as i had the flex section welded in to the dump tube i could feel just with my hand light exhaust escaping all the way around the flex section.(dumptube couldn't just be replaced due to slight variances in the exhaust manifold. see: cast mani) which was a bummer cause i'd just got done systematically getting the downpipe buttoned up. i figured 'this is a brand new flex, must be how its supposed to be'. anyway, i'm just not a fan of flex sections and after what happned to AMG ETR they kinda scare me. don't the ribbed ones fall apart too eventually?
    i need to fab somekinda sound deadening sleeve for the intank walbro too, my car sounds like a late 90's suburban :/
    the hpf sleeve looks snazzy but i don't think itll cut decibels.

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    Can you clarify what you mean by dump tube?

    I have built exhausts without flex sections and do not recommend it. You think your car sounds bad now - wait until the exhaust is rigid from the turbo back and vibrates through the cabin. I think you have a defective flex section to be honest - the ribbed ones are very robust.


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    1 out of 1 members liked this post. Yes Reputation No
    the lil guy on the right with the 2 v bands holding it in. idk the proper term, wastegate dump pipe i guess?
    can i wrap it with anything maybe? i hate it
    Click here to enlarge

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    You can't get that to line up? Dude that's not because of the manifold.. You really think a billet CNC'd manifold is off, vs the exhaust that HPF provided?

    That's the issue? Wow - so HPF is saying the manfiold has variations and that pipe won't line up? Now I know why Leen is insulted. Stainless shrinks and expands dramatically when welded. There's absolutely nothing wrong with the manifold - the pipe is hard to make because they have a hard time welding it without it moving. Sigh. When welding a turbo manifold out of schedule pipe you basically have to go 1/2" at a time or the pipe shifts DRAMATICALLY.


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    twas a joke mayn. besides i'm not taking sides on that issue, it'll come out in the wash. i will say this....there was no f'ing way the one they sent was going to fit. and the 'variance in exhaust manifold' was the explanation i got for why. so i took my old one that did fit and cut their flex section out of their pipe and welded it into mine.

    so i can wrap, yes?
    or wastegate muffler? lol

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    I am not telling you to pick a side but I would just like to say as someone experienced in welding stainless... the "variance" they are seeing is the piping moving. I am extremely disappointed that they gave you that explanation - I didn't realize that was the case. They provided a dump tube with a flex section and it doesn't fit because of variance on the manifold - unreal. The flex section lets you move it around like 1/2" in any direction, or more! This is the BS that doesn't get said... I hope Leen sees this. Literally if you put a TIG at like 100A on a 1 1/4 schedule 304-L stainless pipe for about 3 seconds to go around half the diameter, the pipe changes shape. Which is why when we weld manifolds we bolt our head flange to a 1" piece of steel to sink the heat. Unreal.

    Actually - question - you said you feel exhaust coming through it idling? That means exhaust is reverting back through that wastegate tube since the wastegate isn't open at idle... I think you are discovering some of HPFs issues here.


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    there really isn't alot of room to move around honestly. the flex pipe they sent had an entirely different mandrel bend so i figured the downpipe design had changed from the early ones. i just thought you'd get a kick outta their explanation....

    NOW ANWSER MY QUESTIONS! lol

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    1 out of 1 members liked this post. Yes Reputation No
    Yeah their answer is wild. Sounds like THEY are the ones fcking it up.

    As for wrapping it - I dunno man. It REALLY sounds like a bad flex joint. Do you know who made it? Is it vibrant performance? I have one on the shelf. If you want, I will cap it and pressure test it to see what happens.


  17. #17
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    i need to pull it and see what the inside condition is nowadays.
    yea its a vibrant. you should def test yours out, see what escapes if any, i'd be very interested to know.
    hey, doesn't vibrant make a wastegate muffler for a 44mm?

  18. #18
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    Not sure - if you do that, you change the back pressure behind the wastegate. I'd have to think about the consequences of that, I think it would actually be ok. Back pressure would be lower and the wastegate would vent more. You mean muffle the wastegate separate of the exhaust and dump it separate of the exhaust?

    You can also try this -

    http://www.verociousmotorsports.com/...ellow-Assembly

    I will try and come up with some plugs top test the vibrant flex section tomorrow.


  19. #19
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    ^^^^ that looks solid ^^^^

    keep me posted on your fingertrap. i bet it leaks too, i have no faith in thatched metal... but we'll see !

  20. #20
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    I run a 4" one on my car, no leaks broski

    I will check it tomorrow or this weekend, asap. On mine the liner goes from end to end, the braided steel is just a cover for flex.


  21. #21
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    I would switch out the in-tank pump for an 044 as long as you are stage 2.5 or lower. Walbros are just noisy -- you can get a new one that might be a little better, but it'll still be more suburban than m3...

    As for the flex leak -- it shouldn't and like smallsnail said the wastegate shouldn't even be open at idle anyway. I wouldn't wrap it, if anything I'd get a whole new one independent of hpf (ribbed without weave) and weld it in...

  22. #22
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    Click here to enlarge Originally Posted by spdu4ea Click here to enlarge
    I would switch out the in-tank pump for an 044 as long as you are stage 2.5 or lower. Walbros are just noisy -- you can get a new one that might be a little better, but it'll still be more suburban than m3...

    As for the flex leak -- it shouldn't and like smallsnail said the wastegate shouldn't even be open at idle anyway. I wouldn't wrap it, if anything I'd get a whole new one independent of hpf (ribbed without weave) and weld it in...
    your probably right about not wrapping. the link smallsnails thru up looks promising

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