The headlight will be dim, turn signals may or may not work. Mine didn't. Indicator panel dim. Some find the higher rpm's of driving smooth out the electricals, I had the opposite effect. At idle lights were at their brightest. Why no battery? I got a cheap $30 battery at advanced auto smaller than stock. Works fine I just try to kick start rather than e-start.
As for the exhaust I would think very lean, but not sure, so other members will have to chime in on that.