still have stock ecu, will it be a waist of time to have it installed till i up grade the ecu, will be getting tune

 

Your going to need to recalibrate your ECU for the MAF... a SAFC will be a band-aid. But yes you will need to get your ECU re flashed. It's pointless unless you upgrade to larger injectors at the same time. You will be maxing out the stock injectors (if it's a s13 SR -- 370cc injectors) at around 250ish-270ish whp (some will argue you can reach around 300whp on the stock injectors ... but running over 95% duty cycle is just silly).