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Need Advise : Exhaust


Dualie
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If I'm going to retain the cat, resonator/sliencer and muffler but change to a larger diameter piping all round. Is it worth the effort? Normally, when going to larger diameter piping, how much larger does one need to go?

 

Thank you

 

Keat..

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Neutral Newbie

What's your purpose? From the way you described, I assume you are increasing from extractor down to tail pipe? Pls specify.

 

 

 

Regards

 

 

Lester

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Changing to larger diameter piping doesn't mean the exhaust will flow better when the extractor, cat, muffler etc. still restrict exhaust flow.

 

If exhaust pipe diameter is too big, it may in fact slow down the exhaust flow because the exhaust gas temp. cool faster as it flow down a bigger dia. pipe. Hot air will flow faster.

 

Normally, you should not go beyond 2" dia for a 1.6l car. Anyway, changing exhaust piping only make sense if the stock exhaust manifold is replaced with a more efficient extractor. Of course, that is illegal for most cars in sillypore.

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I've...

  • [*]3.5" pipe to my modified stock intake box [*]High Flow drop-in Filter (Unifilter) [*]Unichip equipped

 

I'm driving a Airtrek 2.0 NA. So any significant effect if I just upsize the original piping? How abt if I add in a 4-2-1 extractor. Pls advise.

 

Thank you

 

Keat..

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Neutral Newbie

In that case, you can put in the 4-2-1 extractor and change the rear muffler to a free flow one but keep the rest of the piping original diameter...nod.gif

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My stock exhaust manifold is the extractor/cat unit. If I change extractor, effectively I'm also decating. Possible just to change 4-2-1 extractor/decat, retain rest of exhaust including muffler. Will result still be the same as "put in the 4-2-1 extractor and change the rear muffler to a free flow one but keep the rest of the piping original diameter"? Pls advise.

 

Thank you

 

Keat..

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Neutral Newbie
(edited)

Gd pt! [thumbsup] that's why I prefer to do Stage 1 1st to see if the effect is detrimental or not.

Edited by GDIzen
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Thank you for your advice thumbsup.gifthumbsup.gifthumbsup.gif

 

Guess I'll visit Man soon for a quote. Btw, since my car is relatively new in S'pore market, there'll be no ready made extractor for it. How do U rate those custom made extractor from Man (or other wkshop)? tongue.gif

 

Thank you

 

Keat..

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Neutral Newbie

Was told at Fong Kim last time that decat would improve mid-range torque, while the muffler job would improve high-end torque. But overall if you enhance the exhaust to give better outflow, I'm told you'll need to look into the intake - to make sure it's properly improved too - else more going out but not enough coming in.

 

Also, if you decat, better be careful of the O2 sensors frequently found in new car cats - can really screw up your ECU if not properly put back.

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I'm in fact looking for improvement in low-mid torque/power. High end doesn't really interest me smile.gif When I fix in a straight thu muffler in my previous car, my low-end suffer like hell. Went back to stock within 1 month wink.gif

 

I've already got a 3.5" pipe feeding to my airbox (stock box opening is abt 2"). Still insuffucient?

 

Thank you

 

Keat..

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Neutral Newbie

If low end is what your are looking for then you should be improving the torque in the lower rpm....and a low pressure turbo setup would be perfect for you...laugh.giflaugh.giflaugh.giflaugh.giflaugh.gif

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Neutral Newbie

Not sure about the sufficiency of 3.5" vs 2". Might depend also on the air coming in - e.g. heard people who tried SRI generally lost power across the low/mid range too.

 

Most cars unfortunately with problem in low/mid torque would be hard to fix - someone suggested these two possibilities -

1. lighter rims - go for as light as you can - but these'll cost $$$$

2. do exhaust wrap/thermal paint - believe it ranges from $180 to $280 depending on your engine layout

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(edited)

What's your opinion of mod that will improve low-mid power/torque? Actually the option of getting a LPT did cross my mind wink.gif Maybe those turbo from k-class cars. nod.gif Anyway, guess I'm limited to whatever bolt-on mod that I feel is useful and let my tuner do whatever magic with my piggy-back can liao.

 

Thank you

 

Keat..

Edited by Dualie
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