The quick calculator I used says that if you apply an additional $500 payment a month to your current payment, you'll be paid off in 15 years, with a savings of $120,662. Use the entire $1000 a month, and your done in 10 years, and have saved $151,542.
30 year fixed, @6.25%, additional payment starting with payment 12
https://www.thinkbank.com/calculators/calc_mortgage.html