Ok ok ok, sooooooo now that this is becoming a thing I feel like a point needs to be brought up:
For Balance to be maintained between these two(assuming the base system of stealth/detection is balanced), stealth absolutely 100% cannot be allowed to modify itself beyond what it already is. What does this mean, and why?
It means that stealth is already an auto-crit if you manage to stealth, and to not modify itself means it can't be allowed to add onto that. Such as by adding more damage specifically from stealth. By giving auto-stealth, extra rolls, extra crit multipliers, extra extra extra.
Now the reason why it can't/shouldn't be done:
The only counter to Stealth is detection. A non-sensor ninja is doomed to simply eat the extra's bought by the stealth person without a chance, reason why? Because apparently auto-rolling a base 10 is allowed, on an already failed roll. "Oh but that doesn't seem so bad" except it is. That person who bought stealth will more than likely take the +13 to it that a rank 4 slot has, which means it's 20+stat vs a non-sensor's 20(max roll)+stat. at even stats, it's physically impossible for the stealth ninja to lose that, as even at a max roll of 20 it just requires the person trying to detect to reroll until they lose.
Now now, I know whats going to be said: If you want to beat stealth you can just take some detection slots. . . That however is a logical conundrum for multiple reasons:
A) Stealth as a slot/focus/ability/mechanic is intrinsically useful in all situations. whether your vs'ing it's opposite(detection) or not, stealth can be used and a heavy advantage gained. IE: Can't be targeted until you leave stealth, auto-crit, jutsus that gain benefits from being in stealth. Where-as it's 'counter' is only useful at all when someone else is using stealth. Detection has no use at all unless your vs'ing a stealth ninja, while the stealth ninja has a use vs everyone. In case you're wondering, that's backwards to how balance should be. The one that applies bonuses universally should be the weaker of the two when it comes head-to-head.
B) An ability that forces someone else to take another, very specific and not useful at all vs everyone else, ability just so they have a chance of staying on even ground is Broken and cancerous to a system. It's how bleach-x became a nuclear arms race of abilities.
"well in dnd you can modify your sneak attacks and stuff" *slaps* stop that. In DnD there is an auto-detection that stops all of your shenanigans called true-sight, and I doubt anyone wants to see that here.
So anyways: If you allow stealth to keep getting stronger and stronger without penalties being applied to it, then there wont be any balance for it unless you start giving detection more universal uses. No matter how much you give detection bonuses vs stealth, as long as stealth can go and face everyone on a minimum of equal grounds, and at a maximum of being broken as hell, there is no true counter-play to stealth.
On a final note: Really, you can spend 23 pp on making stealth op as hell and be useful vs everyone. You can spend 23 pp on making detection kinda ok and only be useful vs that stealth person and really you'd just be lowering there benefits to neutral rather than getting a benefit yourself.
Stop buffing the 'situational' mechanics, because honestly they aren't that situational and give no interesting counter-play in this rule-set.
((There should be a note put in here that My main character is a stealth based ninja, who if all this buffing of stealth is allowed, is about to go op-sneak-Saiyan mode because why not))