Thanks for the comments guys.
Eric, the 04-07 CTS was available with a 190 HP 2.8 V6. My 05 has the 255 HP 3.6 engine. The 2003 CTS and some early 2004'* had an Opel 3.2 HP engine. The 3.6 has the best overall driving experience by far with the most horsepower and VVT. The volant intake has been dyno proven to increase wheel horsepower up to 12. (I have this intake.) So I'm probably pushing right around 267 for horsepower, and pulling 3,509 pounds.
The thing about the CTS is it has a 5-speed automatic transmission so under WOT it might not feel as quick due to how quickly it goes through gears and because it'* a very smooth engine under WOT. But, I can assure you she moves very well. It'* quicker than my mom'* 2000 SSEi. We've had a "go" at it before.
The 00 Impala LS is rated for 8.2 seconds 0-60, the 05 CTS with the 3.6 is rated for 6.7 seconds.