Ah cool. Thanks for the clarification.
I would think even at 290psi 2926 shouldn't have an issue pulling 10-15 passenger cars at track speeds.
When I saw your original question I got curious.
The 300 psi design yields a force of about 172,000 lbs-ft at the piston surface. Unbelievable almost. That said, all the calculations seem to be linear (no squared terms) so from my layman's perspective a drop of 10 psi from the original value of 300, is about a 3 and 1/3rd percent reduction in power.