Anycubic Mega S and Chiron upgrades to make your printer a reliable workhorse (paid links):

Left handed all aluminum Bowden extruder. (left handed on Anycubic printers)

After you get tired of the cheap metal axle sleeve wearing out on the Titan extruders. This is real fun to diagnose by the way since it doesn’t appear as a catastrophic failure at first.  Your prints just start coming out ugly. Anycubic chose to use weak extruder motors and then gear up to compensate.  One of the sketchier Achilles heels on the Chiron.  When changing from a stock extruder to a 1:1 extruder you will need to change the estep values. A stock Titan extruder is set around 405.. I would recommend setting the 1:1 all aluminum  to 100 to start with then calibrate from there. Read about chaining and calibrating estep values for Anycubic extruders here.

Silicon heating block sock

Anti Backlash Spring Loaded Nut & Flexible Couplings

The T8 brass nut that mounts to the frame needs 4xM3 Threads to mount OEM on the Chiron.
The flexible couplers are 5mm to 8mm.

TMC2208 Stepper Motor Driver set for quiet operation an reliability.

When the stock motor drivers fail you get print drift. Irritating but not too bad.. unless it’s your Z axis driver.. bad things man bad things. I replace the stepper motor drivers on any new anycubic printer I get right out of the box.  Noise reduction is a huge benefit here too.