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Discussion Starter · #1 ·
if you put an aftermarket back box instead of the standard evo6 back box does it give more torque or horse power
i need some figures of a dyno test

example

you take the standard downpipe and put a middle section with no cats and aftermarket back box
or you take the same as above but you use the standard evo6 back box does it make any differance in power

regards

andre
going sideways
 
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Discussion Starter · #3 ·
manufacturer of exhausts only want to sell their exhausts so they always say you get more power

if you put an aftermarket rear backbox on you think it has more power because of the sound but forget the sound does it really give you more power

i want a dyno test or some one who has really tested it himself.

andre
 
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Discussion Starter · #4 ·
Good point André,

incidentally I had a chat a few days ago with Phil from Co-Ordsport because I wanted to change my exhaust system on my Mak. He told me that the Mak system is very good and he wouldn't recommend changing it to for example a HKS. Additionally the Swiss Ralliart dealer advised against fitting an aftermarket exhaust because of the possibility of the engine to run lean.

On a modified scoob runing higher boost my mate carried out some tests with different backboxes with a knocklink and a boost gauge. The difference in boost was surprisingly around 0.05bar from a STI bb to a Prodrive one.

On the other hand check out the dyno graph posted by Blow Dog. It shows an impressive gain just from a magnex exhaust. For my liking peak power is too high up on the rev range (at 7000 rpm) and torque hasn't sufficiently increased IMHO.

Mike

Cheers
 
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Discussion Starter · #5 ·
If you reduce the backpressure by changing the exhaust, power might slightly increase but will be higher up. This only makes sense if you have a different ECU with more pressure. The reduced backpressure will then be of use.
 
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Discussion Starter · #6 ·
so claudius what you say is if you use the standard ecu the change of a backbox doesn't make any differance

carefull i only talk about the change of the back box in combination with an aftermarket middle section and decat pipe standard downpipe

andre
going sideways
 
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Discussion Starter · #7 ·
scoobymike

total magnex pipe should gain more power on blowdogs car because you change the middle pipe, cat,backbox and maybe downpipe ok i know it gains power but if blowdog puts his original backbox back on on his remaining magnex pipe will he loose power then

thats my question

sorry for my bad english

andre

going sideways
 
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Discussion Starter · #8 ·
André

as long as you don't run high boosts I don't think by only changing the back box a difference in power will be noticable, at least not on the road. Only a back to back dyno test would give you the definite answer. As I only can comment on the Mak exhaust which has a different muffler than the standard cars I don't think the Mak BB is very restrictive.
Otherwise why should Phil give me the answer I mentioned above if he could have sold an HKS system to me which cost around 450 quid?

Cheers

Mike
 
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Discussion Starter · #9 ·
If you change all the exhaust system including the downpipe on the evo you will really have more power,about 25bhp,but at higher rpm and the torque will be slightly higher or maybe lower than standard and at higher rpm!

That means that you feel a difference in performance but you will have less response under 3500rpm.
I think that if you only change the cat back system,you will have more torque at lower rpm than standard and about 15 bhp improvement.
The parts that really reduce the torque are the downpipe and the de cat.

Anyway I don't like the standard system as it's too restrictive at high rpm and too silent.
Usally the exhaust companies will prommess big bhp,but if you have a look at the supersprint graphics they claim 306bhp on the evo with the full system,26 more bhp,but on others cars as the subaru they just claim 9 more bhp with the complete exhaust!

There are some graphics of a evo vi owner that has more than 300bhp with just the magnex exhaust fitted.

Claudius tryed the ralliart sports ecu on his evo with standard exhaust an the car was even slower!We try the ecu on my evo with complete exhaust and filter,and it was really fast!
 
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Discussion Starter · #10 ·
i have a hayward and scott cat replacement pipe and a midsection and a back box

just have put off my back box put standard on i can not feel and differances besides the sound and i have less fuel cuts but no flames anymorehttp://www.ltregister.f9.co.uk/graphics/sad1.gif border|EQU| 0 align|EQU| absmiddle >

so if you want less sound and max bhp you

change downpipe
cat pipe
midsection
keep the standard back box

keeps the headache away and gives extra bhp
 
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Discussion Starter · #11 ·
My final question is:


DOES A BACK BOX GAIN BESIDES SOUND EXTRA BHP AND TORQUE

AND THE ANSWER IS:
 
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Discussion Starter · #12 ·
a Makkinen version has a differant back box does it give more sound (dont want to) and is it better than the standard one

i had lots of fuel cuts on full throttle with hayward and scott back box put the standard back box back and could floor it againhttp://www.ltregister.f9.co.uk/graphics/happy1.gif border|EQU| 0 align|EQU| absmiddle >
what has happend?

andre
going sideways
 
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Discussion Starter · #13 ·
If you change your whole exhaust system you really need to remap the ECU, otherwise there is not much point. But if you remap the ECU (mainly increased boost) in conjunction with a good exhaust system and a performance airfilter you will see significant changes. My car put out 329bhp on a dyno after that. Of course you can remap the ECU with the standard system, but you will get to it's limits pretty quickly (probably around 300-310bhp). As far as someone recommending to keep the standard system, that can only be meant with no remapping. Otherwise they don't now what they are talking about. The standard system is ridiculously puny, just jack the car up and have a good look at it and how thin the diameter is, the back box doesn't make too much of a difference. Without remapping it doesn't make any sense to change the exhaust from a performance point of view.
 
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Discussion Starter · #14 ·
As I said in my previous post, the higher the boost the more important is the whole exhaust system including the BB.
Next Monday I'll dyno my car. If we find time we change the BB on my mate's scoob which runs around 1.35bar peak and 1.2bar hold boost to see if it makes a difference.
As I don't have another BB than my Mak's standard one I can't test it but I suppose the result of the scoob could give us some hints.

Cheers

Mike
 
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Discussion Starter · #15 ·
thx guys

Scoobymike keep me informed i really want to know the differance in standard and aftermarket backbox

regards

andre
 
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Discussion Starter · #16 ·
Hi André

I hope we can carry out the test. As the Scoob is also turbocharged it should give us some food for thought. As the EVO uses a bigger turbo the exhaust will be even more important.

Mike
 
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Discussion Starter · #17 ·
I have Apexi downpipe, blitz induction kit, and fujitsubo exhaust (minimum diamter 3inches) from the cat back. Along with performance plugs, HT leads etc have seen a big increase in torque. not so much in power
 
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Discussion Starter · #18 ·
Maxi

if you say cat back system do mean the standard cat stays? they always told me that a cat takes away a lot of bhp and torque this is not thru i read youre previous posts

andre
going sideways
 
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Discussion Starter · #19 ·
Andre!

The back box is not the most important part of the exhaust, but if you keep the standard back box, it will be the part of the exhaust that lets less gas out, causing a little more backpressure. This is why your car doesnt have fuel cuts any more when you put the std back box back on. For maximum performance (in case you are interested
 
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Discussion Starter · #20 ·
André,the cat back is the mid pipe and rear silencer.
With it fitted the increase in power is noticeable and the loss in torque at low rpm is none,it's even better!

The decat will give some extra bhp,even more with the downpipe but the torque will be at higher rpm and slightly lower than with the cat back alone!

Anyway at my advice the standard exhaust is to restrictive and silent and I think that is the first part to change on the evo.
I have all the supersprint system but after different tryes,I now have all the supersprint exhaust fitted but with the standard cat,to have a little more torque.I would replace the decat as soon as I fit a new ecu!

STANDARD EXHAUST? BEURK!!!
 
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