Reported on reddit:

I'm trying to test out how well shove damage works on Bunker, so I started to check out some of his specific upgrades. I found out that, the "Please Stand back" upgrade, which gives " "+150% Shove Damage. -10% Attack Damage" actually only gives +50% Shove Damage instead of 150%.

Basically, his shove damage was 35 before upgrading, and should have gone to 40 base. As soon as I picked up the upgrade, it should of shown shove damage as 120, instead it was shown as 60 in the character menu.

I didn't have any (other than the aforementioned chip). The only reason that I noticed that the aforementioned chip wasn't working as it was worded was because I was pausing the game after each level and writing down all the stats that upgraded, as well as all of the chips I picked up. Shove damage was at it's base for that level (Bunker starts at 10 shove damage and increases by 5 per upgrade). Before I picked up the upgrade, she was at 35 shove damage. As soon as I picked it up, she went to 60. Basically, 40 +50% (40*1.5) = 60.

Ahh, I'm re-replying to this instead of editing because I wanted to clarify some things (and make sure that you see them) that you asked that I might have missed in my first response. First, you mentioned that 35 Shove Damage was a very high base value. I wanted to clarify that it wasn't base value, but Shove Damage for Bunker after so many non-shove related upgrades before adding "Please Stand Back". I didn't save the data I used last time so I created some new data to share what I'm talking about:

Base: Shove Damage was 10 (starting without Crowd Control).

1st upgrade: Shove Damage 15 (non-Shove based upgrade)

2nd upgrade: Shove Damage 20 (non-Shove based upgrade)

3rd upgrade: Shove Damage 25 (non-Shove based upgrade)

4th upgrade: Shove Damage 30 (non-Shove based upgrade)

5th upgrade: Shove Damage 35 (non-Shove based upgrade)

6th upgrade: Added "A Taste For It" after 20 shove related kills Shove Damage went from 40 to 60 (my initial testing didn't include this upgrade and this was the point where I added "Please Stand Back" in the previous test, which converted the Shove damage to 60 [40*1.5=60] instead of 100 [40*2.5=100])

7th upgrade: Added "Please Stand Back" Shove Damage 98 (65*1.5=97.5 not 162.5 which would of been 65*[1+1.5] )

8th upgrade: Shove Damage 105 (non-Shove based upgrade)(97.5+5*1.5)

I'm doing some more testing and a lot of the upgrades aren't straight forward. I need to test more, but so far:

The Starting upgrade "Crowd Control" (+100% Shove Damage): increases your initial Shove Damage from 10 to 20 and adds an additional 5 Shove Damage per level (so 10 instead of 5).

"Please Stand Back," the upgrade that this bug report is on, functionally multiplies your current Shove Damage (after adding leveling bonus) by 1.5 and multiples your future leveling bonuses for Shove Damage by 1.5. As an example, if you started out with "Crowd Control," and took "Please Stand Back" as your second upgrade from the machine in game (1st upgrade being non-shove related), then your Shove Damage would be 60 (20 starting + 10 for first upgrade then [20+10+10]*1.5=60). Your next upgrade (assuming that it doesn't give any more bonuses) would give an additional 15 Shove Damage ([5 Base + 5 Crowd Control]*1.5).

"A Taste For It," which states: +1 Shove Damage per monster killed by a Shove (up to 20). Does exactly that, giving up to 20 damage points. The only weird thing with this is that I entered a zone that had a blue pylon that gave 200% Shove Damage in the zone. I didn't upgrade anything and left the zone and my Shove Damage was higher (by more than 20) than before entering the area. I can only think that extra points gained in that zone from "A Taste For It" don't get removed. That, or some other bug related to that pylon.

There's another one that I want to test called "Cowcatcher" that gives +100% Shove Damage. I think I remember that it boosted your current by 100% only when you get it, and doesn't add any additional per level. I wasn't recording the information at the time so I can't be sure though.