If you're planning to run boost don't bother with the LSVTEC setup. A boosted B18b will be plenty. You can divert the funds you would have spent on LSVTEC to build up the engine and safely crank up the boost.

However, I can't say for sure whether 9 psi on a B18B will give more power than, say 7 psi on a LSVTEC motor.

Shingo