Well heres the arguement...

Compression on a 98 LS is what? 9.2:1...

Compression on a 98LS with a b16a/b18c5 head is what? 9.6:1; with a b18c1 head 9.7:1...

9.2:1 is favorable for FI on stock Cast Pistons...

Now, turbocharging an LS with say a T3/t04b 50trim stage3 turbine in a .48A/R turbine housing will make 15psi at around 4,200rpm and take it to redline at 7,000rpm with lots of torque from 2,000rpm to redline...Great Street Power...

Now with LSVtec, you have a head that is meant to redline at say 8,500rpm and a bottom end that is meant to redline at say 7,000rpm...Combine the 2 and you have a motor that no engineer will design as it sits...You will first want more compression and upgraded rodbolts to make reliable power...
Now that power is not nearly gonna come close to 5psi on a turbo LS and its not gonna be as reliable either...

So, you use the strengths of the motor...ie, lower compression, low RPM torque...

Instead of abusing the block with high RPM...