Not without the tournament romset.

Are you planning on making the sub as well?

You can't without the tournament ROM from Papa.

Jackpot increases at game start and when locks lit IIRC in the stock romset.

Levels the playing field as much as possible for tournament play. I suppose there's still lock stealing because it's a physical ball lock.

From the old tournament tracking website:
https://sites.google.com/site/allentownpinball/tournament-rom-mods

Elimination of auto difficulty adjustments to lock lighting. (All locks must be earned, either through left loop spot (if enabled), saucer spot (if enabled), or hitting standups)
Jackpot minimums and maximums settable.
Jackpot advances by lighting locks (as factory) as well as various scores around the playfield.
Added setting to hold off on jackpot collection until all 3 balls launched.
Added setting to require completion in multiball of all 9 lock targets to allow jackpot collection.
Added setting to eliminate extra balls if desired.
Extra ball can award points from 0-9.9million as desired.
No lighting extra ball from A-B, drop bank only.
Added setting to stop spotting of lock targets from middle saucer.
Top saucer maxes out at 150k instead of 500k.
Added custom game setting to allow individual tweaking of timings on million shot, left loop spot timer, drop bank, drain plug, and spinner.
Spinner now resets timer as long as its hit within time period (no more timing out in the middle of a spin).
Added ability to turn off the million shot.
Added ability to turn off all lock spotting on the left loop.
Added ability to turn off the drain plug.
A-B completion will extend drop target timer slightly (if running)

The first ball sits in front of the coil plunger and the other two sit behind it. Switch is what determines how many balls are in there.