I am going to mod a powerwheels car, but want to check on something first. Thanks.

I am not an electrician or car expert but what do you mean? For the racing? What car do you have? I have some friend at work, before he worked in the car service company, he is really a master of car upgrading topic when we talk about it, I would say this is his hobby, maybe he can recommend something.
I can aslo recommend guys who were doing all-electric and lighting in my new house when I moved - it`s here Bates Electric Charleston I don`t know if they serve other cities and if they are dealing with car modifying, you have to connect them to learn, I just can say that they are very responsible and nice people