Welcome to the darkside!
I did pretty much the same thing...... I took the Cross in for some warranty work about 100 miles before the warranty went out, then I walked out with a new Challenger.
Get on Challengertalk.com ...... there's a wealth of info there.
Oh ya..... Cut that huge suitcase muffler off from under the car and straight pipe it. It'll sound wayyyyyyyy better! Then order a Diablosport Predator tuner and a 180 Degree thermostat. You'll have that Hemi flying in no time, women and children will cry when you fly past them, and the tire companies will LOVE you!