NF Mod/Nissan Master Tech
2006 Pathfinder LE, 2003 Frontier SVE
If it's a "real" friend, I charge them my cost for parts and don't charge for labor. Anyone else, I charge $40/hr. x labor guide rate and 20% over my cost for parts (10% if it's a really expensive part). $600 sounds pretty light for all four converters, knock sensor and other parts unless you're using really cheap parts!