Thunderbird question

Hey

I have a 175g Star Thunderbird that is crazy overstable, for me its impossible to throw it. I also have a Star Ape that isnt even that overstable, even for forehand its way too overstable to throw it.

Is it just that thunderbird or are they really that overstable? Can also throw my Surge SS way better than the Thunderbird on a backhand and I don't really have the biggest arm.