With 3sfe you wouldn't require much alteration if you are going for daily drive car - in case you wanna go for some race setup, I doubt it will be uppto your expectations and brake alterations would be first thing required
I have 3sfe auto in my datsun 120Y and it's doing great from last 8 to 9 months - since I am using it as a daily driving car, I don't Risk pumping it hard because of stock differential that is 3.9 and also I have stock brakes.
On the other hand I have smoked an auto reborn nd liana emminent in straight run by a gap of car - this was on phase 6 boulevard that is empty at nights - ps have also tried tails and thought it was not a good idea with auto so never tried again.
For fuel economy since I am running stock differential, gear ratios are high and secondly its auto tou it gives about 9 to 10 km - really depends on how light foot I drive
Now sourcing is a great headache - everyone will give you 6 months warranty but the day it's over, your engine setup start giving a blow - luckily and Alhamdulillah that was not the case with me as it's still running good MA
this is my advice from experience I have had with 3sfe
Plus if you are in Lahore I can give you number of the guy that did my swap - it was all clean swap with zero vibrations MA and all electrical sensors were working!
