I want to buy this for my sons car seat. I was wondering if it would effect the safety? I cant find anything online. When I brought him home from the hospital they told me not to use the strap pads or the extra head padding on his car seat bcuz it effected the way the straps fit him. And that it wasnt crash tested. but would this be the same since its just a cover? It shouldnt effect the way the straps fit around him right?