Make sure to refresh your memory on the stats of the base Warthog in vanilla, here's my current iteration, subject to change;

Damage per pellet: 6
Pellets per shot: 8
Rate of fire: 5
Reload time: 4s
Mag size: 24
Reserve ammo: 160
Stun chance per pellet: 8%
Stun duration: 3s
Ricochet chance per pellet: 25%
Full auto by default
50% move speed penalty while firing
Mass decreased from 4 to 1 and spring stiffness from 75 to 50 (the recoil works like the GK2's)

Upgrade tree:
Tier-1: +1 ROF vs +8 Mag Size
Tier-2: 1.25x reserve ammo vs +1 pellet per shot
Tier-3: 0.67x spread vs +8 Mag Size
Tier-4: +2% stun chance per pellet vs +25% move speed while firing
Tier-5: Turret whip vs +25% ricochet chance

Overclocks:
Mini shells:
2x Mag size multiplier
1.833x Reserve Ammo multiplier
-1 damage per pellet
0x weakpoint damage bonus penalty
+25% move speed while firing

Cycle Overload:
1.33x fire rate
1.5x spread

Dragon's Breath (Pump Action reworked):
0.33x fire rate
0.33x mag size
0.5x reserve ammo
+1 blowthrough
-25% ricochet chance
+100% damage dealt as heat
+150% damage as fire damage to burning targets
1.5x spread

Magnetic Pellet Allignment:
0.66x fire rate
0.5x recoil and spread
+40% weakpoint damage bonus

Lightweight Magazines:
+32 reserve ammo
-1s reload time

Stunner:
Works the same