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Old Aug 3, 2011 | 05:47 PM
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Default Exhaust simple question...

Im getting a bit with the exhaust "bits" as in what i need, is there 3 cats on my bug? 1 uppipe 1 down pipe and 1 cat pipe? plus a mid box or am I way off? Iv been told by the previous owner its got ported " headers" WTF is that lol and can I prove it ? cheers lee
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Old Aug 3, 2011 | 06:24 PM
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Std a Bug WRX (not STi) does indeed have 3 cats as you say. See here:-



You'd need to get under the car and take a photo of the headers (bolted to the underside of the block halves), for us to see if they've been changes to tubular - and, usually, equal length - jobs...

Last edited by joz8968; Aug 3, 2011 at 06:36 PM.
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Old Aug 3, 2011 | 06:30 PM
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Ported headers are the OEM headers which have been gas flowed for better performance........so will look normal

http://scoobytuner.com/graphics/ExhuastDiagram.jpg

is a diagram of the bug WRX

Shaunh
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Old Aug 3, 2011 | 06:46 PM
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Cheers lads cleared it up for me, so basically a turbo back exhaust plus an uppipe to fully decat, is there a good amont of torque/hp doing this b4 a remap? cheers lee
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Old Aug 3, 2011 | 06:52 PM
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Oops, sorry you said ported, not tubular.

But yeah, basically for up to 400bhp:-

*A set of harvey's OEM ported headers (if yours aren't) + OEM ported uppipe (harvey will advise on uppipe type/size etc.)

* New Age pattern bellmouth decat d/p (replaces the OEM 2-part dual-cat job), plus decent system.

Can use either a 2.5" or 3" d/p + system for upto 400bhp.
For over 400bhp then need to have the 3" exhaust parts, plus a move to equal-length tubular headers/uppipe...


Changing to the above exhaust parts will maxmise any power gains in the remap.

Last edited by joz8968; Aug 3, 2011 at 06:56 PM.
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Old Aug 3, 2011 | 08:39 PM
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Originally Posted by joz8968
Oops, sorry you said ported, not tubular.

But yeah, basically for up to 400bhp:-

*A set of harvey's OEM ported headers (if yours aren't) + OEM ported uppipe (harvey will advise on uppipe type/size etc.)

* New Age pattern bellmouth decat d/p (replaces the OEM 2-part dual-cat job), plus decent system.

Can use either a 2.5" or 3" d/p + system for upto 400bhp.
For over 400bhp then need to have the 3" exhaust parts, plus a move to equal-length tubular headers/uppipe...


Changing to the above exhaust parts will maxmise any power gains in the remap.
Nice 1 dude exactly what i needed to know, up to 400 will be plenty its standard now bar uprated brakes and tein suspension
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Old Aug 3, 2011 | 09:35 PM
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Would this be any good for a decat? http://www.ebay.co.uk/itm/SUBARU-IMP...item3368f0b3f9 cheers lee
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Old Aug 4, 2011 | 04:22 PM
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Ok just found out its got a cat - back system and ported headers, how can I measure the pipe bore without taking it off is that possible?
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Old Aug 4, 2011 | 04:40 PM
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Wrap a tape measure round it to find the circumference.

Then do this calc:-

diameter = circumference divided by 3.14159

That'll give the outer dia. -- so subtract about 6mm (c.3mm for each opposing sidewalls thickness) = inner diameter. Simples

Last edited by joz8968; Aug 4, 2011 at 04:51 PM.
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Old Aug 4, 2011 | 04:43 PM
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Originally Posted by joz8968
Wrap a tape measure round it to find the circumference.

Then do this calc:-

diameter = circumference divided by 3.14
Now if I would have listened in school I prob would have known that lol cheers
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Old Aug 4, 2011 | 04:46 PM
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Im guessing it will be either 2.5 or 3 inch ?
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Old Aug 4, 2011 | 04:48 PM
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Nah, won't it'll be that huge.

Prob more like in the region of 40mm ID (or about 1.6")

Last edited by joz8968; Aug 4, 2011 at 04:52 PM.
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Old Aug 4, 2011 | 04:50 PM
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Originally Posted by leeturbo2000
Originally Posted by joz8968
Wrap a tape measure round it to find the circumference.

Then do this calc:-

diameter = circumference divided by 3.14159
Now if I would have listened in school I prob would have known that lol cheers
...Then follow this:-

That'll give the outer dia. -- so subtract about 6mm (c.3mm for each opposing sidewalls thickness) = inner diameter. Simples

Last edited by joz8968; Aug 4, 2011 at 04:51 PM.
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Old Aug 4, 2011 | 04:53 PM
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Originally Posted by joz8968
Nah, won't it'll be that huge.

Prob more like in the region of 40mm ID (or about 1.6")
Really? it is a SS catback system though?
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Old Aug 4, 2011 | 04:53 PM
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Il just measure it and find out lol
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Old Aug 4, 2011 | 04:59 PM
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MY BAD!

I thought you said uppipe!!! LOL

It's this static air and heat -- I need a lie down.


Obviously yes, it will be either 2.5 or 3 inch for the exhaust sytem - a quick measure will confirm

If it is a 3", check to see if the downpipe/centre section flanges isn't a reduced 2.5" one....

Last edited by joz8968; Aug 4, 2011 at 05:02 PM.
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Old Aug 4, 2011 | 05:15 PM
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LOL no worries appreciate the advice m8ty, find out more about this car everyday, its got a KnN panel filter, SS catback and an LMA(?) BOV but never been mapped? So im thinking uppipe and downpipe....jobs a good en.......for now lol
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