that is a good point, on standard engine mounts the movement could cause the silicone hose to slip. still i do like this the look of this as a modification. it would be good to see how the neuspeed one compares in size etc.
looking at the neuspeed discharge pipe there is a machined lips to ensure the silicone hoses doesnt slip off etc, it look like yours doesnt have that, and with the aluminium tube being so smooth it could be a possibility. maybe a welded lip around the ends could help reduce the likelihood of it happening??
http://www.neuspeed.com/products/product_details.asp?app=95|GV&type=11<ype=ns_euro&p_id=2004