I make 389 whp at 20 psi and I am at 100% duty cycle on my RC 550's, B&M FPR modifier at 60psi static pressure, and 255 lph (low pressure) walbro fuel pump at 7000 RPMs. I'm upgrading to RC 670's this week and going to retune.

It all depends on how much power you want to make. If you're not going to push the limits of the fuel system and won't be pushing a crap load of boost then you don't need to run a really low CR. It's all about what your goals are.