Conventional wisdom says, yes a stiffer front bar will increase understeer. In the Z's case, the stiff bar helps reduce body roll which in turn keeps a larger tire contact patch on the front tires giving you a better turn-in and ultimately, reducing understeer. At least, that is my layman's understanding.
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2011 370Z 6MT Sport Gun Metallic | ARC | CJM | Ecutek | FI | Fujimura | R2C | SPL | Stillen | TWM | Z1 | ZSpeed | |