I was the tuning king back in the day when I had my GSX. I ran 780cc injectors with a 50 trim controlled by SAFC w/datalogger and my tune was dead on with no timing being pulled and seeing 15 degrees from 4k - redline! It was a PITA and it took alot of time to do it, but its doable. I didnt have a wideband either. Just tuned on EGTs and timing. Another thing, I didnt have a chipped ECU either. Just a stock 98 GSX ECU.