I wouldn't recommend splicing into the existing loom. New wires, thicker than stock, positive directly to the battery. The main battery earth is on the engine near the R/R so heavy gauge from the R/R to the engine and then on to the battery. New inline fuse on the positive direct to the battery.

Cheers, Richard
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09 America, Staintune Pipes, K&N, Breathe, Hagon Nitros, AI & O2 removed, tune 20184 (modified), MTX-L a/f gauge