How Do I scale a whole assembly

I Have an RZR 1000 Turbo File its a huge file was an iges file when I got it, but the scale is off how do I fix this? IF I scale each File and try to put it back together it no longer lines up with the planes. I don't like the fact I cant pick a scale to Bring in the Iges and I don't like the fact there is not an Easy way to do this. Any UG users out there I know that Software can handle this.