Didnt mean it in a bad way, but its jus way more complex than most seem to think, esp when there a huge amount of compressor and turbine options on BW turbos.
You cant properly spec a turbo without knowing the full spec of the engine, and you cant fully spec an engine unless you know what turbo you getting.
Basically, doing it properly, you spec the engine and turbo at the same time to work well together.
So is there anything set in stone, ie anything youve already bought/ordered, or a power level you going for, or how you want it to drive, etc etc etc.
I could give you my opinions if I got something to go on.