Currently, the IFV-6 is too lightly armored. I have tested firing at it with both the 120mm long of the Kuma and the 125mm of the T-100, and found it to being able to sustain only one to two hits from the front arc. The tracks actually soak up much more damage than the hull can.
To compare, the M2A1 can take at least three hits from the front arc from the 120mm long unless hit in the turret ring or when suffering a penetrating hit in the engine or turret, and blows up after four to five hits.
Place IFV-6 at the end of the runway, place other tank at 1km distance, fire at frontal and/or side arcs and observe single or two shots kills. (Bad angles seem to improve kill rate, but I have to do more testing to confirm.)
See below for correction measures.
The IFV-6 is basically a Slammer with the turret removed. The removed weight of the turret is then re-added as armor on all sides, including the bottom of the hull. If anything, the IFV-6 should be able to at -least- sustain as many hits as the Slammer, and on average be able to take more than its MBT counterpart.
tl;dr: IFV-6 needs Slammer frontal arc armor both on front and sides, Slammer side armor on the back and top.
Cheers
Insta