If I were you I would ring up insurers and put in the details as if you were trying to renew, because when I changed from my old Leon cupra r to my evo 9 with no no claims bonus it didn't go up by nearly as much as I thought it would for the rest of the year, but come renewal time with my 1 years no claims it was over 2k and I only managed to bring it down to 1800 by raising my excess, and I'm 28 with no points and I live in a nice area. A 21 year old getting a similar quote to me in similar circumstances seems a bit far fetched. Do your homework mate