my kit (Speed-Racing) clears average speed bumps BUT has issues (especially the front lip) with ramps that are at a steep angle and similar. But my kit is VERY low, I think much lower than the Nismo kit.
I actually broke my front lip when coming back from europe last summer, on a ferry ramp, despite having cleared it fine in and out of the ferry on my way to france... (same ferry, same ramps...)
New front lip is at my house now, but planning on mounting it only for shows and 1/4 miles etc since it isn't that practical on everyday driving