On the summons for racing, does it indicate if you were charged with stunt driving - more than 50 km/h over the limit or stunt driving - marked departure from the lawful rate of speed? Not much I can really tell you, other than the officer chose to use s. 172 (stunt driving, racing) of the Highway Traffic Act instead of just s. 128 (speeding), and also did not want to knock down the speed to 49 over. Do you think the officer lost sight of you for a while (more than a couple of seconds) before he pulled you over? If he did lose sight of you for an extended period before catching up... well... remember the 17-year-old who was caught doing 239 in an 80 zone last year? He beat the charge, pretty much for that exact reason.
Take notes of the incident, and go back and take some photographs with a cheap $6 disposable camera showing that there are no houses, hence no risk of hitting a kid that may be Trick or Treating on a deserted rural highway. The reason for the disposable camera is that digital photographs can be easily altered, so some courts will not accept them. Toronto usually will accept digitals if the original data card is submitted and the photographer is present, but it doesn't sound like you were nabbed in Toronto.
For any serious HTA charge, I always recommend some sort of professional legal help, which, in this case, would be a paralegal. The more info you have for the paralegal, the better. There's also a form to fill out at the bottom of this page that you can use to get a quote. The consequences of being convicted are quite severe (large fine, additional suspension, huge insurance increase) for this charge, so the risk of "going it alone" is very high if you have little or no experience in court. A professional should be able to, at the very least, get it down to just regular speeding and get rid of the stunt driving part of it.