The M-Max, or any other derestrictor allows for keeping a stock wire harness stock. If your not worried about questions concering why the looms is all cut up at time of sale, then no, its no better then a wire splice.
With the wire splice you can go better then the M-Max by doing the GPS splice as well. If I recall, the M-Max doesn't include this (but I could be wrong).
If you want the good setup, go with the HRC box, and wiring loom.
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Charles Gallant