I just ordered a K&M lightning spring and a Creep Killer from promoted pawn. Anyone have this combo? Between them, they advertise half the trigger travel and half the weight of the stock trigger. I didn't want to shell out the full $200 for a Delta trigger job from Promoted Pawn.

Please report your experience with them.
I recommend the AMP engineering trigger, had that for a while.  It just feels better, tactile improvement, no performance claims.

So, I received both parts.

K&M Lightening Spring: Packaging sucked. Arrived loose in a small tiny bubble mailer with a business card inside it. No directions or anything. For $35 a spring they could at least throw in a printed page of instructions or something. They have an installation video on their website which is helpful. Despite that, this spring was a BITCH to install compared to other rifles whose triggers I've replaced. I was really only able to do it using a tool that came with my Shooting Sight ARX trigger. The posterior arm of the spring is a better fit than the stock unit but should still be about 1mm shorter - I scratched the inside of my trigger housing installing it the way they recommend. Anyway, now that it's in, the trigger is definitely noticeably lighter than stock. So I'd say it delivers on its promise (I don't have a trigger gauge so I can't give exact measurements, but I am satisfied that I got my money's worth of trigger weight improvement).

Creep Killer: Packaging a bit better but still not great. It was sent in a non-padded USPS priority envelope and the heat-sealed bag had failed upon arrival (the part was out of the bag, loose in the envelope. The Creep Killer, for those who don't know, is basically a little plastic trigger stop. The Gen 1 was installed on the disconnector pin from outside the trigger pack. This Gen 2 version is installed on the trigger slide pin inside the pack. Installation is therefore more difficult than the Gen 1, but still took only a couple of minutes. I'm not sure why they were redesigned this way - was anyone having problems with the Gen 1 falling off or something? The part itself appears to be 3D printed and is fairly rough-looking. Nonetheless, once installed, it does what it claims to do. Its shape limits the motion of the trigger in such a way as to reduce both the pre-travel (creep) and post-travel of the trigger. I think the claim of half the trigger distance is probably roughly accurate.

In sum, for $70 or so, I think the pairing of these two upgrades is worth the money. No one will mistake it for a Geissele or Shooting Sight trigger, but my PS90's trigger is definitely substantially improved from its shitty, shitty stock form. Time will tell if the parts are durable, but a trigger spring and stop aren't subjected to much battering, so I am optimistic.

Good info, thanks for taking the time to type this up!  Does anyone else have any experiences to report with improving the PS90 trigger?

Shooting Sight is working on a PS9 hammer pack, but who knows when it will be done. You could buy the reduced pull Man Kave Gen 1 hammer.

Yea, I wish he'd get that thing done and release it. I'd buy two in a hearbeat. Until then I love the ManKave upgrades.

Maybe I was just lucky but I think my gen 3 ps90 has an overall decent trigger pull, and not just by buildup standards. I might try the upgrades OP mentioned but I've had much much worse from the factory- my recent cz scorpion had the worst trigger of any I have felt.