I removed the APEX spring kit from my SD9 and installed the Wesbaun SD/SDVE spring kit. IMHO, it's 10X better than the APEX kit.
My trigger pull weight is almost 5 lbs. I have shot almost 300 rds. and no problems.
S&W SD VE Trigger Spring Kit for Smith & Wesson SD9 SD40 SD9VE SD40VE 107-120 - Wesbaun Gun Springs