Editing Terrain Mesh Scenery?

Hi, first off apologies if this is in the wrong section. If it is mods then move it by all means!
Now is there any way of modifying Terrain Mesh Scenery? I have just downloaded the mesh available from this excellent site here http://www.simviation.com/fsdterrainsrtm.htm, and it is by far the best I have seen! But its still not quite right on Anglesey, north wales! See I work at RAF valley, so that is one of my favorite areas to fly round (bit sad I know) but it seems like the hills and 'humps' arent quite high enough. ie the snowdonia range is pretty small in the sim but its HUGE from where I stand on the runways!
So is there a way of editing it? I'd be more than happy to share it
Thanks
Paul
Now is there any way of modifying Terrain Mesh Scenery? I have just downloaded the mesh available from this excellent site here http://www.simviation.com/fsdterrainsrtm.htm, and it is by far the best I have seen! But its still not quite right on Anglesey, north wales! See I work at RAF valley, so that is one of my favorite areas to fly round (bit sad I know) but it seems like the hills and 'humps' arent quite high enough. ie the snowdonia range is pretty small in the sim but its HUGE from where I stand on the runways!
So is there a way of editing it? I'd be more than happy to share it

Thanks
Paul