Is it warrantied by Subaru? Better yet, if they install it, it should not void any factory warranty. If Best Buy does it, Subaru can use that as an excuse to deny warranty coverage.
I should mention that Subaru has not and never will "void" a warranty. They can deny paying for a claim based on a specific modification and things directly effected as such, but a warranty can not be fully voided. If you fully prep a new car for racing and its still under the factory warranty (gutted, built motor etc), but the rear defogger switch goes out.. You could have it repaired under the factory warranty easy peasy.
That said, the Subaru remote start would probably be a plug in harness. Instead of best buy using vampire clips/splices to tap your wiring.
Edited by Ibreakstuff, 20 August 2014 - 12:45 AM.