Right the workout maths is right, but that does not mean that the motor stops pulling once all the timing is used up... 13000 RPM would be where no more timing is added but the motor will continue to accelerate, so that's not a right answer there.
I run 50/18 have 200ACC and start at 2000RPM the elogger logs my max RPM on a 13.5 at 45000 using your maths my car would only be doing 12000 RPM as the boost stops this plainly is NOT the case so please lets get some correct facts / maths on here.