Wow... 20 over could be upwards of $500. I've known some jurisdictions to charge up to $25 per mile over, plus put points on your license... so be prepared for your insurance rates to go up as well. Sorry... I've been caught daydreaming before; my last ticket was for 4 mph over and it was $135 with fines, costs, etc.
Go to court and sometimes the policeman who issued the ticket, fails to show up. Meaning the judge has to dismiss the ticket. If you do lose, ask for traffic school. You have to pay for it, but it does not effect your insurance rates.
You should be very careful how fast you drive in a residential area, which is where most of the 25 mph zones seem to be. How would you feel if you hit a child that ran out in front of your car, or killed someone's dog or cat. Take your medicine and learn your lesson. It only takes a second to kill someone or something. I have sympathy for the situation you find yourself in, believe me I do, but you are going to get hit hard for this. Think of it as an ounce of prevention that prevents future accidents that will do more than cost you a fine.