Turbo manifold or partially complete kit
 

I am in the UK and to collect the parts for a custom turbo kit starting with the manifold and downpipe as there is virtually no one in the UK that supplies them.

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You need to put a little more detail in this WTB

Does it matter if it's a top mount, rear mount, bottom mount, horse mount?

There are quite a few different parts for each system.
There are also quite a few different ways to mount the IC and route the plumbing.

I'm afraid the way you are approaching this might net you parts for a bunch on different systems that won't go together.

Edit: Sort of based this post off your other post here
https://www.rx8club.com/series-i-major-horsepower-upgrades-93/diy-turbo-kit-224679/

BTW you can use the Cobb to Tune the Greddy kit.

I will consider anything if the downpipe is included.
Intercooler plumbing wont be a problem, its the manifold that i cannot buy locally or build myself.