I have played with different power curves (particularly area under the curve) with the sim from launch to finish and the limiting factor, for me anyway, is traction. As power begins to go over a certain level at the launch, elapsed times start to increase. The reason for that is that the tire slip numbers start to increase to too high of a level during the beginning part of the launch. It looks like there is a sweet spot of power that you want to use through the launch to maintain just the right amount of traction. A certain percentage of tire slip is actually desirable with slicks. Around 20-22%. But that number depends on the tire you're using too. I understand that drag radials don't work very well with any slip.
If you find that you are dumping a lot of exhaust energy through the wastegate at the launch just to maintain traction, you could probably get away with a larger exhaust housing. If you're already using a large a/r, you could probably get away with a larger turbine wheel, or less wheel trim. The compromise, of course there's always a compromise with turbocharger sizing, is that it will be a little harder to spool the turbo up to launch power setting. It just depends on what your tolerance is for a slower spool up.
That's what makes the nitrous so nice. You can throw the slow spool concern right out the window.
There is one factor that you can count on by going to a larger exhaust side, you will make more top end power. Be aware that you can go too large on the exhaust side. You want it to be small enough to be able to power the compressor to the boost level you're targeting. For instance, I'm targeting a minimum 40 psi max boost level with this new build. If I am unable to build 40 psi boost with the wastegate clamped shut, then I will know that the turbine is too large. Did you get that, Norbs?
Because of the current gear in the car, we won't be able to give it the extra 15+ psi at BG that I think the turbo has in it