well done weikee, cant imagine u can changed it by yourself. BTW you are right, brass valve is much much reliable than PVC ball valve.
It is very good infor for those end user who not install yet 1.
Js share some little infor with you, if you have another 3M pre-filter(model:AP055T) before AP902, then your AP902 filter can be more lasting.  
because replacement AP055T pre-filter cost is cheaper a lot than AP902 filter..

Actually the reason why people buy ap902 is because of the convenience of without backwash just change cartridge once a year and the compact size. If you install the small ap055t, it is so small,definitely you need to change it more frequent and troublesome. Adding it will make your overall installation look ugly n bulky.

My advise, if your water is very dirty, you have high consumption and landed property use sand filter like my perfect steel. If condo which do not have place for backwash and limited space then get 3m ap902.

Trust me as i installed and tested ap902 close to two years in my house with high usage (all rooms with 10" rain shower and a strong grundfos water pump), filter got clogged in 10 months, then i manually backwash it to prolong the capacity hahahaha.