It took me about that long acutally. Most likley because I have never done anything remotley close to that with cars. But they do it all the time so who knows...
BTW: My Saleen kit is authentic too, not the greatest quality
You dont have anything really listed about nitrous but questions always come up about it, so heres a decent thread i started a while back all about it if you want to use it..:shrug: Nitrous Thread