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3inch exhaust onto std size d/pipe

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Old 21 July 2005, 10:18 PM
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FASTER MIKE!!
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Default 3inch exhaust onto std size d/pipe

will a 3 inch center pipe fit onto a std size down pipe? or do i need a center section with a reduced size pipe at the downpipe end?

cheers mike
Old 21 July 2005, 10:30 PM
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dr_jones
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Originally Posted by FASTER MIKE!!
will a 3 inch center pipe fit onto a std size down pipe? or do i need a center section with a reduced size pipe at the downpipe end?

cheers mike
Standard D/P is 2.5 inch so you'd need some sort of reducer - it's normal to go the other way though - 3" D/P reducing to 2.5 and then 2.5 middle and rear - the thinking being that as the gasses cool the need for a 3" centre and rear section becomes less...

Oh and I'm sure hayward and scott could sort you out BTW.
Old 21 July 2005, 10:32 PM
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FASTER MIKE!!
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thats what i've already got 3inch down pipe reducing to 2.5 just wondered if the likes of the hks blitz 3inch systems, the pipes reduce to 2.5 at the down pipe end?

mike
Old 21 July 2005, 10:35 PM
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stevebt
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blitz and hks do reduce to 2.5" as i had to get mine altered so it would be full 3"
Old 21 July 2005, 10:42 PM
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FASTER MIKE!!
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cheers steve thats cleared things up.what it is, ive bought a second hand back box which is 3inch, so i ordered a what i thought was a 3inch center section(magnex) which i thought would be a 3inch bore, but when it arrived its just a 2.5inch with a enlarged end for a 3inch back box, sounds like if i get a true 3inch center it will be too much hassel/expence to have it convered to fit my down pipe.

mike
Old 21 July 2005, 11:13 PM
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cossie01
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I have a 3" system on my car, so I bought a 3" (all the way through) HKS de-cat for it.

Only thing was, the bloke that measured the bore of the centre section didn't think to check what bore size it was at the flange to the front pipe, and it turned out to be 2.5" there.

However I have still managed to fit my 3" de-cat to the 2.5" flange and it's sealed without a problem.
Old 21 July 2005, 11:30 PM
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FASTER MIKE!!
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so what your saying cossie is that a true 3inch center should seal into the 2.5inch down pipe, in theory anyhow. now i'm confused what to do. stick with it or get a 3inch center

mike

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Old 22 July 2005, 12:07 AM
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i had an HKS system on my car and pulled it off due to having a 2.5" section that joined the down pipe. i then got a hayward and scott centre made to fit my car which was dedicated 3" all the way , but it didnt fit with the HKS backbox so i then bought a blitz nurspec and that had a 2.5" setion which joins the downpipe but instead of adding my centre i then paid to have the blitz altered so its 3" all the way. i now have a brand new unused 3" hayward and scott centre in my garage but im hanging onto it incase the blitz is too loud
Old 22 July 2005, 10:06 AM
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Jay m A
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Some 3" centre sections will fit to the OE downpipe, Scoobymania and Revolution for starters. The flange on these have the same dimensions as OE for the hole centres, so they bolt on with no fitting issues.
Old 22 July 2005, 09:09 PM
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ive got a H+S 3" down-pipe with 2.5" flange which fits onto my blitz nur spec r
also 2.5" flange to down-pipe but then is 3" all the way to tail-pipe

im thinking of cutting off the flanges at down-pipe and centre and make a 3 and a bit inch pipe to sleeve over them so its literally 3" all the way from turbo to tail-pipe
Old 22 July 2005, 09:41 PM
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cossie01
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Originally Posted by FASTER MIKE!!
so what your saying cossie is that a true 3inch center should seal into the 2.5inch down pipe, in theory anyhow. now i'm confused what to do. stick with it or get a 3inch center

mike
Don't see why not, mines done the other way round, 3" decat into 2.5" flange
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