Mitevo7

Hello to seniors and pros , i'm new here ... My car is 2006 sentra auto tranny, i've been trying to add up some torque to improve the acceleration of my car , so far i've done drop in filter , Voltage Stabilizer (don know if they do help), grounding cables, Pivot ignition spark earth, and finally full exhaust systems with full 1.75" pipings (4-2-1 to center muffler to bullet to rear muffler SFlow) ... But somehow i still feel a bit heavy from 2k to 4k while accelerating on low gear, normally its second gear ... Guys do u have any suggestion that could help to improve more the acceleration in low RPM ???