Oh, btw.
As I've noted in previous posts, the pipelauncher would be designed to work for existing rockets. But once there were functioning pipelaunchers then modifications could be done to rockets so that they could get more advantage from a pipelauncher (this is normal in any technical development).
One advantage could be putting more propellent in the rocket- the rocket wouldn't *need* to accelerate as quickly.
Another advantage I just thought of was that since a pipelaucher is accelerating the rocket at around 1 gee, it's "environment" at ignition is the same as though it were launching from a "world" with 2 gees- which means any system using gravity feed would have twice the power- or you might be able to use gravity feed instead pumps. Of course there also could be problems with starting ignition in a 2 gees environment which might mean that ignition needs to be started after the pipelauncher acceleration.