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  • Member
  • Member For: 16y 5m 27d
  • Gender: Male
  • Location: Sydney, New South Wales, Australia

Hey guys

Just wondering - has anyone tried a twin three inch exhaust? I crunched some numbers - twin 3 inch pipes give a greater area than a single 4 inch pipe (hence more flow), and would be better for ground clearance?

Your thoughts would be appreciated.

Chris

2007 BF MkII

Ex Chaser

Stock as a rock - for now...

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https://www.fordxr6turbo.com/forum/topic/54977-twin-3-exhaust/
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  • Forged Member
  • Lifetime Members
  • Member For: 18y 2m 19d
  • Gender: Male
  • Location: SW Sydney

It would almost be too big Chris! Not too mention I don't think you'd get it up and over the rear axle/diff area. If you could dump it before the diff it has potential to flow a great deal, but it would be loud as all hell!

:bowdown:

  • Toughest BA Turbo
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  • Member For: 22y 4m 2d
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Good for 1000rwkw (lol).

You should match your exhaust size to your required power output.

Ideally pipe size should reduce in size mid way through the exhaust to keep up gas flow as gas cools, and reduce turbulence, and improve torque; as with the exhaust I now use (Tunehouse THR with 5" cat).

Even the original stock BA exhaust that I reviewed early 2004 employed that principle, reducing from twin 2.25" to twin 2" at the rear.

Bigger is definitely not always better.

Brian

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  • Member For: 18y 11m 6d
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We did a similar system a few months ago, but Pats right, twin 3inch pipes wouldnt go through the diff area, so it merged into a single 4inch and into a straight through 4inch muffler.

Main reason for this approach was flow through the "mid section", which is where the greatest flow is needed.

There's a few Ts getting around with this style of exhuast, very effective if designed and build well.

Only negetive is price, due to extra piping/parts and labour to build... which is why a single 3.5 or 4inch is a more popular choice.

  • Member
  • Member For: 16y 5m 27d
  • Gender: Male
  • Location: Sydney, New South Wales, Australia

Thanks for the feedback guys, I wasn't sure how much clearance there was over the diff/irs area. I am planning my modifications for 600hp / 450kw - what would the optimum pipe size be? I don't want silly loud, but of course I need plenty of flow.

  • flame magnet
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twin 2.5" works well, and can easily go to an outlet each side of rear. a bit more exy though. 3.5" single is ideal, and cheaper to. expect prices to start at $1500.00. :spoton:

Edited by fordriver1
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  • Member For: 18y 3m 4d
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  • Location: Dianella, West Oz

For 450rwkw I would advise a 4" system. SMB, THR & the soon to be released Nizpro exhaust spring to mind!

A 3.5" system might get you there, but you will have less back pressure with the larger system and you should make the power with a little less boost!

  • Member
  • Member For: 16y 5m 27d
  • Gender: Male
  • Location: Sydney, New South Wales, Australia

had a look at the smb system, I really like their cast 4" header pipe, very well made. at $3k for the full system though, I need to start saving up!

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Iv got the 4" SMB system. Its a great exhaust system...

Dont quote me on this, but your tuner may be able to get the system a little cheaper (trade price)... Might not happen though but it might be a good idea to ask.

CES are another exhaust manufacturer in the same class as these others. Excellent reputation but im pretty sure they are also in the same price bracket, maybe more!

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