Congrats on the car!
Like King of Jericho said, if you install an E93 (convertible) M3 front swaybar (it costs about $250), you'll be staying in warranty and it will eliminate 90% of the body roll. A full coilover system is another way to improve the performance of the car. The BMW sport suspension only consists of springs, which I am not a fan of for the price. I know KW offers a warranty on all their coilovers / suspension components for at least two years. That doesn't match BMW's 4 year warranty, but you gotta give up a little security to have some fun.
Also, it's great you found a BMW employee who's cool with mods, but I would make sure to remove the Juicebox chip whenever taking the car to the dealership. Dealerships can and will deny warranty work if they have an inkling that the tune might have even in the slightest affected whatever warranty work you're bringing the car in for. So it's best to return the car as close to stock as possible. Some things (like intakes, midpipes, axleback exhaust..) they probably won't really care about and are safe to keep on. Other stuff, like a chip/tune or downpipes, they're generally not as cool with.
Anyway, take some pictures and keep us updated on your impressions! Congrats again!
