I replaced the door speakers with some $100 kicker ks68 speakers and it made a HUGE difference. Very happy now with modest investment.
2011 Kona Blue GT Premium Automatic
Livernois 93 Tune - C&L CAI - Roush Axleback - 19inch GT500 wheels/tires - Eibach Pro Springs - Steeda Adj.Panhard Bar - Kicker KS-68 door speakers
12.8 111mph - on skinny stock tires lots of spinning!