It makes it very hard to mount the suspension when you cut out the wheel wells as most of the wheel well is needed.
Try and cut as much away as you can without having to remove the mounting points.
You will find that most models you do you wont really neat to cut the wells out as you should get a good drop without having to do it.
For memory about the only one i had to do was when i slammed my VW as the wheels were so huge.
