Um...no. At the track, with drag radials or slicks, I guarantee my twincharged car would destroy most turbo cars with the same internal mods. I only have a ST2 cam and 105# springs. If I was to upgrade to a ST5 cam, some ported heads, 130# springs, and up the boost to 20psi, I guarantee I would decimate mos, if not all turbo 3.8s out there (minus DarkHorizon who's Fiero weighs half of what a GP does)
The OP is right about how the power is distributed. The supercharger is there for low end power and it spools the bigger turbo faster. Most turbo GPs run a T61 turbo so it makes some power around 3500rpms. A properly setup twincharged setup (like mine) will be able to spin a larger turbo (T67 in my case) at around the same, if not lower, rpms. I'm at full spool at 3000rpms, and making a lot more power than a T61 would be making at those rpms.
WAY WAY WAY incorrect info here. The supercharger is NOT a restriction when it comes to a twincharged setup. It's a positive displacement blower, so it literally takes everything that is put in front of it and slings it into the motor. The best analogy I've heard is this: Think of the blower as a garbage can that can normally hold 50 gallons of trash. his is a normal GTP motor with the M90. Now, lets say you have a trash compactor and you put all of your trash into the compactor before you put i in the trash can. You can fit a lo more trash into the trash can after it's been compacted, right? This is how a twincharged setup works.
Also, spinning wheels is not something that should be corrected be limiting the power of the motor. Upgrading to better tires and learning how to launch a high powered car on the street is how you compensate for spinning wheels.