If you do a 3" or 4" spindle, it will widen the front about 1.5-2" per side. So 3-4" total.
If you do a spacer, it won't widen it at all. They don't come in 3" though... only 1.25" and 2.5" I believe. (And then the springs will sag a little too, so subract another 1/2" to 1" off of those numbers.)
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