Each squig bomb, and there are six, has a BS of 2 and a range of 18". They are single use as explode with the bomb. They have S8, AP-2 and D6 damage. Now that is pretty cool indeed and their deaths are ignored for the purposes of morale.
If we close the distance to the target the boyz can use Tankbusta Bombs with R6", Grenade D3, S8, AP-2 and D D6. Not bad for Orks and the D3 grenade is a big help to increase the volume of hits as is the D6 damage, especially against multi wound vehicles.
The thing that really sets them apart though is the Tank Hunters rule. This means that they can re-roll failed hit rolls when attacking vehicles. Oh yes indeedy folks. This really gives them an edge. In effect it doubles the number of hits achievable.
And for the Squigs .... they hit on a 2+ with a re-roll. In my book that is six guaranteed hits then. For shooting this is as good as it gets!
Now just imagine that there is a particular vehicle that you really want to take out. Weirdboy use Da Jump to move the Tankbustas within 9". Deploy the Bomb Squigs and throw the Tank Busta bombs. So what are we talking as averages against a T7 vehicle?
Bomb Squigs - 6 hits needing 3+ to wound so that is 4 wounds D6 should make it 12 and AP-2 should mean only a 6 will save so with 2 saves that is 10 wounds.
Tankbusta bombs - 5 hits, re-roll the 10 miss's another 3 hits, thats 8, D3 grenade should make it 16 hits needing 3+ to wound call that 10 wounds, D6 should make it 30 and AP-2 should mean only a 6 will save so with 5 saves that is 25 wounds.
In summary - No more vehicle - it is merely a pile of smoking metal with some very happy Tankbusta Boyz standing nearby taking selfies.