You can run as much boost as you want with a "street" chip, as long as no knock is experienced. The difference between a "street" and a race chip is mostly timing and fuel. Altgh the boost "curve" may be more aggressive on a race chip, when using either chip, you should control max boost by the length of the wastegate actuator rod.
If you have 110 octane gas in the tank and run 20psi with a "92" street chip w/o knocking, it is a given that the same car with a "108" race chip at 20psi, will go faster. More timing = more power.
c&cgn is correct. The idle parameters are usually quite the same in a manufacturers street vs. race chip for the same injector setup. Accordingly, you shouldn't notice a difference at idle. Part throttle cruising is when a chip runs in closed loop at its best. Regardless of the chip (well, most anyway), the ECM is always attempting stochiometric AFRs on the highway at cruise.