Cheaper than the OEM battery, and about $150 more than a high quality johnson controls battery of the same size. Exide/Die Hard are a bout 160 cheaper. It's got like 15-20% more output and reserve to boot. I'd say its well worth the extra $$ if you use the X's electronics when the engine isnt running.

So far, Jegs had it the cheapest at $285 (when I bought mine a couple months back).

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2011 Sapphire Black X5D
Burger Tuning JBD
Lux H8 V4 Angel Eye LEDs