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Discussion Starter · #1 ·
My Dad wants a stainless steel exhaust system for his 96 9000 Aero.
Abbott at this current time only supply an exhaust system using 304 grade 2.5" stainless steel.
Also he is in the process of buying a Maptun stage 3 ecu which will put bhp at around 300bhp (with other toys!).

Will the 2.5" pipe be able to handle power in excess of 300bhp? At this moment, it will only be from the cat-back (flexi included). And would a 3" downpipe help the system?
 

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I thought that the Maptun stage 3 was designed for use with the JT 3" system (including sport cat) and JR air filter. You may find that hardware alterations such as the Abbott 2.5" system may upset things.

Maptun do do custom ECUs so it may be worthwhile speaking to them before purchasing your ECU.
 

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I had a full Abbott SS system, but when I went for a custom (stage 5ish) software remap from Maptun, I changed the downpipe to a 3".

There's a couple of reasons for this. Firstly, mild steel is more immune to thermal stress cracking than the SS used in most systems. Secondly, the extra volume helps to cool the exhaust gasses by allowing them to expand and thirdly it reduces spool up time.

When last dynoed, despite having some fuelling/knock problems, it was putting out 309hp.
 

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I was talking to the Maptun supplier in australia, and he has a 97 model 9000 aero with Stage 4 upgrade, and a 2.5" SS Abbott exhaust. he says that only because he is looking at stage 5 that he will change over to the 3". (i will be looking at buying his 2.5" off him when i get my aero at the start of next year.)
 

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Discussion Starter · #5 ·
Originally posted by Mark E:
[qb]I had a full Abbott SS system, but when I went for a custom (stage 5ish) software remap from Maptun, I changed the downpipe to a 3".

There's a couple of reasons for this. Firstly, mild steel is more immune to thermal stress cracking than the SS used in most systems. Secondly, the extra volume helps to cool the exhaust gasses by allowing them to expand and thirdly it reduces spool up time.

When last dynoed, despite having some fuelling/knock problems, it was putting out 309hp. [/qb][/b]
I take you have kept the Abbott exhaust? If so, which downpipe did you purchase?
 

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Originally posted by Scotty Mc:
[qb]My Dad wants a stainless steel exhaust system for his 96 9000 Aero.
Abbott at this current time only supply an exhaust system using 304 grade 2.5" stainless steel.
Also he is in the process of buying a Maptun stage 3 ecu which will put bhp at around 300bhp (with other toys!).
[/qb][/b]
Perhaps he should have held off a little on the Maptun ECU for a few months, because Maptun are soon to be offering a 3" stainless steel exhaust system (check the Maptun website), and I bet it'll be a lot cheaper than the Abbott one as well....
 

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Discussion Starter · #9 ·
Originally posted by aero-less-pilot:
[qb] QUOTE
Originally posted by Scotty Mc:
[qb] My Dad wants a stainless steel exhaust system for his 96 9000 Aero.
Abbott at this current time only supply an exhaust system using 304 grade 2.5" stainless steel.
Also he is in the process of buying a Maptun stage 3 ecu which will put bhp at around 300bhp (with other toys!).
[/qb][/b]
Perhaps he should have held off a little on the Maptun ECU for a few months, because Maptun are soon to be offering a 3" stainless steel exhaust system (check the Maptun website), and I bet it'll be a lot cheaper than the Abbott one as well.... [/qb][/b][/quote]We've been on to Maptun numerous times about this but still have had no response as to when they will be available
 

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This is an e-mail I received from Maptun a week or so ago in response to my query on when they will be offering their new system

Hi!

Today, we can olny offer what JT offers,
In a couple of mounth we can offer our own exhaust systems.
this system will have a 4" almost round finish.

/F

Fredrik Bengtsson

Maptun Performance AB
 

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Scott MC
Will the 2.5" pipe be able to handle power in excess of 300bhp? At this moment, it will only be from the cat-back (flexi included). And would a 3" downpipe help the system?  [/b]
The issue with increased power is, as we all learned in thermodynamics, heat. A stock Aero will produce quite high exhaust gas temperatures. The stock diameter of the downpipe is 2.25". A 2.5" diameter downpipe increases the flow area by about 16%. A larger flow area will reduce the exhaust gas temperatures (EGT's) and every degree drop in EGT's leads to at least a degree drop on the intake side. A 3" downpipe increases the flow area by 80% over the stock pipe - with turboed vehicles, bigger is usually better. To get the full benefit of this, the cat' should also have a 3" inlet. The cat' is the 2nd most restrictive element, after the downpipe. After the cat', there's marginal difference between diameters, as the turbo can't 'see' that far downstream. Some feel that converging the diamter, after the cat', offers better mid-range torque, but I've never seen any figures to prove it. Anyway, if it were me, I would argue that the prerequisite for any Maptun software would be a 3" downpipe - not so much for the power, but for the less harsh, heatwise, operating conditions.
 

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I have recently fitted a Stage 3 Maptun ECU upgrade to the aero complete with the 3" JT pipe and sport cat. I am very pleased with the increased performance, the car is more responsive in each gear and does'nt half shift now (not that it did'nt before )
 

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My custom Hayward & Scott 3" centre and back section compliments the JT3" dp and sport cat very well. BSR do a 3" stainless dp and cat (which I wish I had known about).

PS: The JT sport cat is not free flow at all - it is a standard 400 cell ceramic cat. Wish I had bought the race cat now. May get back to Elkparts on that one.

Zip
 

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Originally posted by Zip:
[qb] BSR do a 3" stainless dp and cat (which I wish I had known about).
[/qb][/b]
Why would you want to have a stainless steel DP? Have you ever seen a rusted through DP? Stainless steel is much more prone to cracking due to execssive heat - and the DP is by far the hottest part of the exhaust.

Yours,

Philip
 

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For some reason I have let my self believe that the JT DP is SS. Rest of that exhaust isn't, I know that for sure.
 

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Originally posted by philip hs:
[qb]Why would you want to have a stainless steel DP? Have you ever seen a rusted through DP? Stainless steel is much more prone to cracking due to execssive heat - and the DP is by far the hottest part of the exhaust.[/qb][/b]
I think it depends on the grade of stainless. The JT is definitely aluminised mild steel while the Abbott downpipe is stainless, as far as I know. I've never heard of a JT downpipe cracking but I know of at least one cracked Abbott downpipe.
 

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I think you will find that JT started changing their down pipe to stainless a little while ago with the connecting pipe in aluminised. The current ads quote it as s/s for the 9-5 but still aluminised for the 9000.
I am currently looking for a NON s/s downpipe/performance cat in 2.75 or 3 inch for my 9-5 but not having much luck. Why? I would rather ceramic coat a normal steel pipe, mainly for noise reasons but also for the reduced potential for cracking. I have no problems using stainless after the cat but I am not convinced it is the best material for the downpipe in a turbo application. Anyone have any reasons or benefits for using stainless here?
 

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The benefits of a SS downpipe, assuming it's a crack-resitant (I've also heard it depends on the grade) are the same as the rest of the system I guess- corrosion resistance.

Apart from the life, I've heard the other benefit of the corrosion resistance of SS is that it keeps the inside of the tube smooth, thus aiding gas flow.
 

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Thanks Mark
My main complaint is that in my experience, full s/s systems tend to have a very "tinny" resonance to them that does not appeal to me as much as a good old throaty rumble (sorry, my V8 background showing through). Surely Longevity and appearance can be addressed by ceramic coating which also has performance benefits?
 
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