Well there really isn't a whole lot to launching an AT (power braking) and you don't need to upshift because regardless of gear you put it in the TCU will shift at redline to keep you from over revving the transmission.

I'd be suprised if you could get better than 17 second pass on just a GS-T exhaust. The fastest I ever went when my car was AT was a 16.9. I know Shuwa got a 16.8 in his. I believe there is an Avenger on here that went 16.7 before he went turbo. All of us had considerable mods on those passes. But you won't know until you try it. Take her to the track and find out.