At that stage if you look closely you can see that the far left front grid and right rear grid are missing and that is where I had my ramps. I also have a picture of my ramps in there.
In this video you can see the boys using the ramps (kind of).
I have another video of Harry going down the ramp, but it is really dark and you can't see the ramps very well. You can see the ramp in the background in this one.
http://i8.photobucket.com/albums/a30...s/101_0094.jpg
(I couldn't get it to not distort the thread)