I pretty sure it is because a staggered set would throw off the computers stability program cause you are messing with the geometric parameters.....this is what i've heard and i think it makes perfect sense for xi models since its moving at all corners.
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BMW E92 335i
retired: 04 BMW M3 | 05 Honda S2000 | 03 BMW 330ci | 01 Honda Prelude | 99 Acura Type-R
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