k04 is the best option.......very good spool and keep 1.5 bar to the red line with all needed components, injectors, maf and a good cooling. Fuel pump not need to be change if it is in good conditions. If you works with 9.5:1 engine you will have more retards but at 1.4-1.5 bar boost will be ok.....BUT>>>>>>>>>>>>>>>>K04 will btoken the RODS after some boost if the torques is agresive!

Its funny when someone builds a 12.5:1 turbo setup thinking they are going to make SO much more than a low compression setup. Every time the dyno shows much less difference than expected and then octane requirements make them not pump gas friendly.

The more torque you want to make at a given displacement the higher the pressure in the cylinder is and the lower the compression ratio needs to be.

For 450whp on pump fuel on 1.8T I would use 8.0:1 CR...

You can think all you want. I know.
Without octane boosting it will be. It sounds like you never in your life built or ran anything on pump gas that made any significant hp/liter.
Also, on a built engine or a hobby car there is no reason ever to have a compression ratio that is going to limit your power output and raise your EGT, as the only thing that will suffer with a lower CR is fuel efficiency, and at higher CR everything BUT fuel efficiency suffers. Reliability, thermals, power output etc.

I don't know why you keep on repeating this, because this is blatantly false. All things being equal to make a certain torque you need a certain cylinder charge.
This cylinder charge will be compressed based on the compression ratio. If you have leaky cams with overlap, it just means you need more flow to get the same cylinder charge.
In the end you still have to get and compress the same amount of charge into the cylinder. And what cams you have does not matter. Cams do not affect this whatsoever. Engine breathing will determine how much charge pressure you need to run to get a certain cylinder charge, but not how much torque it's going to make with the same cylinder charge being compressed after the valves are shut.
If at a given cylinder charge you are knock limited, you will make more power with a lower CR and the same cylinder charge, and of course there is less heat.

What does affect CR is if someone cuts a chunk out of the combustion chamber, after which the volume of the cylinder has to be measured using liquid to again know the true compression ratio.
If material is removed from the cylinder head, then the 8.5:1 piston can become 7.8:1 really quickly.

Btw, it's a really shitty idea to have overlap on a turbo engine higher in the rev range when backpressure starts being a factor. It completely destroys power output.

Nothing to say to such internet gods.

My recommendation is to curb your enthusiasm until you have actually achieved something.
I don't need to look at what "guys are making" because I have my own hands on experience.
And there's a huge difference between a short dyno pull and sustained EGT.

I'm not sure why I'm thinking the G25 housing is too small because the 2.7 guys are using it as well as other platforms with 4+ cylinders. EGTs will definitely be higher and get hotter sooner but the speed at which it increases and the temp probably isn't as much as I might be thinking.

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