Hello your choice of Sakura is a good one as i have one too, read through rctech-sakura zero s section, it contains good info. Some neccassary hopups i think are replacing the plastic hex wheel adaptors with the alloy ones and the turnbuckles for the titanium set.
Firstly for 540 you need to loosen the belts otherwise the friction will rob you of speed, you will need ALLOY SPUR GEAR ADAPTOR, and GEAR SHAFT SET and 19T PULLEY. The zero s has a tendency to be loose in the rear (oversteer) i recommend getting 5.75 and 6.0 optional springs, 5.5 is standard but are too hard for the rear, i use 6.0 in the rear and 5.75 occasionally if i need more steering. Another way to improve rear traction is to shorten the rear track width, i am using X1 rear arms to do this or you can use the optional narrow rear blocks.Shock oil try 35wt but without the softer rear springs try 40f 30r, 1.5* camber f/r, 0.5* toe out front, 3*rear, droop 5 f/r hope this helps feel free to ask any questions