I had few AC car, for my parts. I would prefer RC mart or even just order from Asso parts house, no need to wait. Cat shop will have more parts of X factory, but AC, just a little.
T4 is a good car, but no track in HK. HK is a touring haven, buggy hell.
U should better go to some China indoor track to test how good is your T4, then u will feel what is real buggy.