It is a great kit. The only problem is the one-piece flexible tracks that is a bit tight (unable to simulate sag) but overall the kit is a very good quality kit.
Two things you can do with the tracks:
1.) Build the tank with the sideskirts on to cover the "non-sagging" tracks.
2.) As what I did. Stretch the tracks a little bit to loosen it but do this carefully or you might overstretch it.
Good luck.