Ruko ruko ruko bhai, baat suno...
L13z1 is faster obviously, because its NOT idsi for one thing. Secondly it houses around 10 or 15 more BHP, may be I am wrong but it has more Horses, that's for sure...
L15A Comes in PKDM Honda City Vtec Steermatic and in Honda Fit Aria JDM, difference lies in aria being i-Dsi and Steeroo being a VTEC beast.
Fit aria's motor is a loser, totally. All you'be upgrading in ur car is the "fuel expense"...
Find your self a L15A VTEC motor and marry it to the 5 speed manual tranny already in your car.
As for more practical info on the swap, Contact wadday detailing walay ustaad jee Usman Salariya... #Detailing Crew, lahore.
P.S: both L15A's have different codes, this is just the motor tag, full tags I can't remember but you can detect the steeroo engine from the VTEC cams in just a matter of seconds. 