compressor maps don't mean shit unless you know exactly what configuration they were using during the test because all of that changes as soon as you order a different a/r or exhaust wheel plus compressor maps are made using a non real world compressor "dyno" using natural gas.

Billet technology is going to be a very important thing in the future for making big power on smaller turbos, meaning, a 61mm billet turbo will be able to EASILY make 650+.. instead of waiting for lightning to strike. they are already getting upwards or 85-90lbs per minute on a fucking billet 6262 wheel.

You can never calculate ahead of time what your pressure ratio is going to be, you can only do it with on car testing, and then adjust AR housings and wheels to get the ratio you want, which is usually 1:1 for most setups. .8:1 for high compression.

Don't get hard for ball bearing turbos because "they spool faster" because thats not what they are built for and really truly do not spool faster, maybe 100rpm. BB is for DURABILITY, and this is strait from the man that designs the turbos for a very well known turbo producer.