The PFC adds 18 ft-lbs on the low end, and EDIT: Lucky_317 (didn't include _317), EDIT: Illusive (left an "l" out of his name) etc have no problem launching 2.0's which they also do with the stock ecu.
Yes, the SC is instant torque from idle on up. It may be hard for that person, but it wouldn't be if he/she had the right setup. The Blitz SC sucks for drag racing anyway so why bother launching. Turbo is the way to go on the Celica for drag racing. And heck, you say "a lot more power than stock"? If you want, with electronic boost control you can launch at such low psi you're barely any more than stock. I gave mrtomcat's example of his TURBO GTS pulling a 1.85 s 60 ft. I didn't need to, and I don't need to say any more.