9:1 or 8.5:1

[Tsi]

What CR to run is going to be entirely up to you. A higher CR will produce more power at a given level of boost. It will also spool a turbo faster. Every good thing has its price though...with a higher CR you're going to have to do a better job tuning to avoid knock and detonation. You're going to have to run lower boost with a higher CR, than say with a lower CR. 8:5:1 seems to be the way to go for the 4G63T's