Lifting the IFS rig puts more acute angles and associated forces on the attached components, including the steering...
Augmenting or replacing stock components to restore the geomentry you had at stock height, and or going with a stronger system, helps to avoid steering failure over time.
People have wheeled for years on a stock steering system and a lift....or a matter of months....before having a problem. (YMMV)
So - Its something to plan on, albeit you don't necessarily need to get them at the same time...but have the budget for it clear in case you need it sooner rather than later.
The BL doesn't affect the steering, just the SL....and larger tires.
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- TJ
2001 Xterra '03 VG33, SE 5 spd, 305/70/16's, Revolvers, UBSkidderz, Doubled AAL's, 3"SL/2"BL, winch/bumpers, skids, sliders, OBA, Snorkel, pine stripes....
Friends don't let friends drive stock.
http://www.gifsoup.com/view/501230/tj-tackling-crawlers-ridge-o.gif