B6 A4 Daily driver big turbo build need some input!!!

[EuroxS4]

So long story short my brother decided that it's time to build a motor for his car.

So right now car is stock 2005 b6 a4 1.8t Amb Quattro 6 speed manual.

Looking to go big turbo.Since I'll be doing all the work I could use some input from you guys.

Realistic goal is around 400whp only because it looks like that's all the stock trans can take.

So here's a list I came up with as far as parts go.

Amb block
Scat rods 20mm pins
Aeb pistons
South bend stage 3 clutch
Aeb head
Possibly cams we'll see
040 pump
630cc Siemens injectors
Fmic
High flow cat
3" cat back
Top mount turbo manifold either t3 or t4
Borg Warner turbo s200sxe 52 or 57mm???

Engine mounts
Trans mounts
S4 throttle body
Aeb intake or custom


So far that's all I got as far as the big stuff goes obviously new crank bearings and rods bearings and all new necessary gaskets head bolts among other things.

My main concern is spool of the turbo and whether I should be lowering compression???ideally I would assume car will run 25+ psi of boost maybe 30+ not sure if it's possible looking for some answers.Comment below.