IS250IS250

Hi all I recently purchased my 2nd IS250 and love the car to death. Only had it 5 weeks. Performance and comfort. It felt like old model performance wise. But now I am not sure. There might be a small slip or drop in performance. I don't know if I am over paranoid or it is just bad luck week's in. Furthermore sometimes I hear a blowing of the exhaust but it sounds more like cardboard in bicycle spokes. But can only hear in built up areas where noise rebounds. Any advice? Trip to the garage?