So I currently have Headers, Stillen True Dual and Stillen TP and tuned on Uprev, but I'm getting sick of the rasp so I'm planning on changing to HFC. My question is would really need to retune it after i do this swap? I can't get an e-tune from Uprev since i don't have the wideband O2 Sensor, and the closest Uprev dealer/tuner shop is 5 hours away.

Any help here is appreciated, thanks guys.

 

With HFCs your motor will be a little less efficient, and AFR will be richer. It won't harm.