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Performance Manifold For Is200 And Altezza


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OK gents... having seen various threads on here with no successful outcomes...

i thought i would post this.

I have access to performance stainless steel headers for either is200 or altezza.

These will be £400 + p&p. ( Thats p&p from myself... not from the Far East!!!) and i can order them as and when you guys order them...

I would prefer to order a batch, but as this often causes problems, i am prepared to order them as and when you guys want them...

let me know gents..

Scott :driving:

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mr scotty,

any info on these

ie: what r&d has been done

what performance gains are expected

have they been dyno`ed

do they allow for superchargers

i know mr prolex has been researching these but has rejected so many for false or no performance gains, skimping on testing could actually result in lower performance figures

dont understand the far eastern bit either , are they coming from the far east ?

or is just postage local?

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Which format do these manifolds come in for the six cylinder engine? 6-3-1 or 6-2-1?

I spent many happy years tinkering with Triumph 2.5PI's and you need a 6-3-1 on ANY straight six. The trouble is that the headers need to be paired up 1 and 6, 2 and 5, 3 and 4. Clearly to maintain the same pressure drop becomes a tricky exercise in pipework fabrication. Most so-called specialists opt out and connect 1,2,3 and 4,5,6 together as a 6-2-1.

The reason for pairing up a 6-3-1 with pairs at opposite ends of the block is that it's good to connect cylinders 360degrees apart (in terms of crankshaft rotation) so that you get a scavenging effect

I've never found out the firing order on an IS200 but it’s either 153624 (like a Triumph) or 142635 (like a BMW??). This is because a six has a firing stroke every 120 degrees of crankshaft rotation so it either turns one way or the other. The pistons come up and down in pairs but each pair (1 and 6, 2 and 5, 3 and 4) is phased 120degres apart. Obviously the pair in question don't fire together but alternate in a four stroke style. The slug of exhaust gas from one cylinder is on its way down the header by the time the slug from its mate starts its journey. The first slug creates a partial vacuum in it wake which helps to draw the second slug along - hence scavenging or 'extractor'.

Of course this is really ancient technology; maybe I'm a 30 something old f@rt and things have moved on. I guess chipping it and bolting on a blower makes this all a bit academic.

Enough oily fingered rambling – after all I'm too scared to take my IS apart!!


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You aksed for pictures of a 6-3-1 manifold.

See this link

Chris was the ONLY person I would deal with for my Triumph. However since I wrote it off and got a sensible car I'm hoping he'll get interested in the IS.

I thnik that's more than enough manifold spiel from me.


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  • 2 weeks later...

Has anyone had one of these fitted yet? what is the fit like? They dont look bad actually but need to know more.

Looking at them, they have good long Primary's for torque balance and the pattern is good for peak power.

Need to know several things:

1. Internal bore - is it matched or greater to the exhaust port for diameter

2. material grade.

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scott, the manifold might go on a none supercharged car, but the only thing that i can see, is there is no point on the top right of the manifold to bolt part of the supercharger cradle (as on the oem manifold) this could be a problem ? its the holes that the heat deflectors screw into. i might be wrong but thats the way it looks to me ? cheers gordon

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