what gear ratio best for turbo application

What would be the best gear ratio for a turbo application. I currently have 4:10 gears. I was thinking either a 373 or 342. This is for a m6 for the street. hopefully will be pushing 600rwhp

for 600rwhp prolly 3.42/3.55 nothing more.

Even with those gears, you may not make full boost in first gear, as it revs so quick.

FWIW I'm running 3:42's....seems to run pretty good.

My 4:10s really dont let the turbo to spool at all