Thank Geezer! It's awesome to get some appreciation for this. As you have mentioned the turbo manifold and rack conversion I will share some more details about them! I know you didn't really ask for more info about the manifold but I like talking about it
A fair bit of work went into that manifold. Indeed it was the most difficult project I have ever tackled. I learned new technology such as 3D scanning and pipe routing in Solidworks The flanges and merge collector pieces were all CNC machined which allowed for perfect fitment when assembling. I've never welded something like this before (well i welded some bike frames a decade ago but that's different) so some of the welding is not great but definitely functional. All runners are equal length and as short as I could get without cutting custom bends so hopefully it will perform reasonably.
Toolpath for one section of the merge collector. I tried using 4 axis machining method before this but it kept snagging so I went for 3D machining with a ball end.
Toolpath showing porting of the turbo flange. This was to save work with the die grinder and to cut a tiny relief so that the pipes were exactly located.
Merge collector sitting on jig showing how good alignment was (you'd hope so for a CNC process!)
Now for the rack conversion. I'll cover it as a guide as that might be more informative.
Requirments: (What I used, if you are up to this you will figure out substitutes I am sure)
*GN Sigma
*R32 Crossmember/K-Frame
*S13 Coilovers
*Adapter plates for S13 coilovers to fit GN strut towers (I CNC'd mine, could make more easily)
*S13 Steering rack (I used a Hicas one as that is what I had)
*R31 lower control arms
*S13 CA18DET brakes and lines
*S13 steering column
*Astra power steering pump
*Custom Hydraulic lines
*Lathe
*Welder
*Grinder
Firstly cut the engine mounts of the GN and R31 racks. Use some common sense here and take some time as it it a pain in the a. I'm certain this is covered in another thread but anyway.
Comparison of each:
R32 xmember (top) GN mounts (Bottom)
You will need to notch out the inside of the GN mounts a lot and also cut the 32 crossmember down at the ends. Do this in many steps and keep checking fitment as shown as you go. If you do this badly you will end up with something crooked or have a real bad time welding later. You can just sit the lot on a jack and lift it in and out of the car as you need. The column is sitting there in this pic but don't bother yet.
Once you have it all cut, you need to weld it. I made up some shafts to go in the LCA holes to help line it up. If you can't figure out how to line the parts up, you probably need another project to hone you skills first.

Here I drilled an extra hole to allow less track. I am unsure how much bump steer it will add so I'm not sure if i will use them. You will also see a sneaky bit of RHS you will need to add to strengthen the assembly up.

If you do it well and paint it black it should look stock(ish)
Ok, just got sick of writing! I'll add more later! If you look for powerstump on FB you will find more pics there. Next installment I will deal with the column.