This kit does improve the FOC Grimlock figure a lot, fixing its major weakness. Fairly well-done given the constraint.
A reminder: this is a "vintage" item and cannot be shipped along with the "regular" items in your stack. So I ended up paying shipping cost for this kit.

This item was greatly delayed, but it was well worth the wait. Almost all the issues with the early release seem to have been addressed leading me to believe the delay was for some tweaking to make it better. While not great it is better than any other items out there to fix the issue of the gap in FoC Grimlocks Dino modes chest. Worth getting if you want to make a good Grimlock a great Grimlock, but it still has it's drawbacks so 4 out of 5 stars and worth buying to me.

This was a good addition to the figure as far as filling the chest and remaining in place. I am disappointed however that the gun is loose in the fist and wobbles, and the pieces hard to fit into the arm holes and armor holes when separated. I am overall pleased with the product because I mainly wanted it to fill the chest, but other than that the other pieces are a disappointment.

This product does fill the chest in quite well. However, it does not stay attached during transformation well. The craftsmanship is not the best. Mine arrived with a broken post, easily fixed with some super glue, but still unfortunate. The gun is a nice addition, but not a selling point. If you really love the FOC Grimlock and want the chest filler, I would wait till this goes on sale.

I got this upgrade kit mainly for the chest filler. Grimlock looks like a hollowed out cheap plastic toy without it....in MY opinion. This kit comes in this little box which is cool. The parts are packed nicely and theyre all the right color. The instructions are trash. Seriously. I had to look at videos to see where and what I was doing. There are 3 configurations. Chest filler, Armored, and "Classic". The first two are really the same thing. You attach the kit and it stays on. Swinging out on arms from dino to bot it helps secure the arms in place and makes a real difference in the appearance. It stays attached the whole time. The third mode is abysmal. The armored wings get their own attachable joints that his dino arms snap away from the body and on too then on to the armored areas the kit forms. In this mode you must detach and reattach the kit every time you transform it. When I got this kit attached it was a floppy mess. Others had the same experience. The only thing that does work is the Armored mode and the filler in the chest cavity. The gun is also loose. I think its an ok set. Its a little pricey for something that barely works but it does improve the figure.