Hey there,
If you don't plan to upgrade your wheels anytime soon, widening out the track with stock rims is the next best thing. When I bought my CPO stinger, it already came with spacers (20mm i think) and lowering springs on the front and rear. I haven't gotten around to checking the brand closely but my wheels stick out just enough to cover the wheel gap. Sorry, I don't have any pics up yet to show.
They do help with cornering, around town and windy roads, but I can't say how they perform on a track environment. I've put wheel spacers on all my vehicles and as long as you torque them properly, and check every oil change, they improve aesthetically and performance (some) wise. Its like that old skool pontiac grand prix commercial "wider is better"