Track racing bike-build

Where did you get 750W from??

And what would the 25cm equal in time (my maths isn't working today) it seems like a pretty big gain for a loss of 200g on a bike, simply going from the steel nittos to a carbon bar would probably do that, yet it's never reflected in the times.

750W is the average power needed to accelerate 100kg of bike+rider to 15m/s (33.5mph) in 15s.

Kinetic energy = 0.5 x 100 x 15^2 = 22500J
Power = 22500/15 = 750W

25cm as you cross the line at 15m/s is 0.25/15 = 0.016s. Bear in mind that that only applies to acceleration, any steady speed effort is almost completely unaffected by the mass of your bike, apart from a tiny change in rolling resistance. Because most of the acceleration happens early in the lap (when you have a bigger surplus of output power over combined drag + rolling resistance), you spend most of the time doing a speed where more than half your power is consumed by drag, so that is always where your resources should be spent, ahead of trying to lighten the bike.