well, you can goto your market and buy a Bando belt for like 3 to 400 rupees and see if it works.. if you get a good belt, it will work.. I have one belt, bought for 350 rupees, installed and running in a corolla, working fine and its been like 20000 kilometers now..
recently i bought bando serpentine belt for this engine, it didn't work, slipping and squeaking bad.. and now I bought the original belt from a toyota authorised sales shop for 3400 rupees.. and its working fine.. so check the cheap bando belt before you buy the original one.. people say that it works.. didn't for me.. or maybe I just got a piece of shit belt... I'll try again next time..
use hi-octane, mine feels much smoother on hi octane and no knocking what so ever..