@Devin: Not to worry! Sometimes the stock open cell foam (white stuff?) will work very well as they are usually much softer. Often the softer foam will make the car a little easier to drive and in some cases can increase traction. What kind of track are you on and what kind of tires?

All that being said, generally speaking tires don't last that long so you will get a chance to mount up another set with different foams. It may be worth it to do that now so you can compare directly and see what you like best. Nothing better than switching between packs and timing your laps to see.