I think you are missing the major point I was trying to make: Improving maximum speeds on short sections" gets you next door to nothing.
If I were to redo my little calcs above using 160 mph instead of 150, then for 160 versus 125 you gain 63 whole seconds in TEN MILES if the speed limit before was 125 mph, and you have an increased power consumption of about 60% per mile to do this. In other words, if you want to save 10 minutes, you have got to have 100 miles of track that is already good for 125 mph that you can raise to 160 mph, and that had better be a near to continuous 100 miles. Also, if you have curves that are good for 125 mph and no more, they would still be good for 125 mph and no more unless you can modify those curves. Dlerach mentioned 1 degree curves as being good for 125 mph under the Acela: Based on the old SE = 0.0007 V^2 D formula, this would indicate a balancing superelevation of 10.93 inches, which is extremely high, so I am not sure that is correct. The usual maximum superelevation is 4 inches on lines carrying high freight cars such as piggyback or double stacks, and 6 inches on lines that either are passenger only or limited to passengers and low center of gravity freight equipment and loads, so, if given 6 inches actual, this leaves an unbalance of near 5 inches. The usual is 3 inches, but with tilting equipment you can do more, so let's assume the Acela can handle 5 inches of unbalance. Churning the SE formula around, this says that for 160 mph operation you must have curves of not greater than 0 degrees 36 minutes. Again, we are dealing with not the direct ratio of speeds but of speed squared. (A one degree curve, chord definition, has a radius of 5,729.51 feet, and a 0d 36m curve has a radius of 9,549.25 feet. Degree of curve is defined as the change in direction over a chord distance of 100 feet.)
I am saying all this to say that realistically if you want to increase run time, you deal with the slow areas, and then maybe think about raising the speed limit. To quote an article on this subject that was in the Railway Gazette International quite a few years ago, "The best way to go fast is to avoid going slow."
Yes, I realize that politicians tend to live in fantasyland on many things and one is virtually everything involving railroads, but none the less we had better be able to understand what the realities are and not go into swooning fits believing what they tell us. The CAHSR is an outstanding of a very good and essentially necessary system that has been turned into a boondoggle by political manipulations. There is a saying that you probably dare not say out loud in current conditions, which is the first exercise in developing any major facility is shoot all the involved politicians.