You're right, it's not perfect for all cars....but 11.0 on a stock pulley GTP is too rich. I'm going to argue, because I've been doing this for 11 years, and the days of choking out KR with fuel are long past. Concerning the fact that the AFR adder table is going to drop it even more, this car's tune is ****ed from one end to the other.
The only way to fix it, is flash it back to stock, and tweak about 7 things and call it good.