To start off, the cars are very similar in weight. Yours peaks at 306 hp at 6800 rpm. The grand prix peaks at 260 hp at 5400. The grand prix makes more torque. It VERY likely has a much wider powerband, where yours doesn't get 300-hp strong until the end. The grand prix has a 4-speed auto, you have either a 5-speed auto or a 6-speed manual. Stock vs. stock, you'll probably win. If that grand prix is modified, you're probably toast.
It will depend a lot on your skill and his, whether you have an auto or manual, whether your car is awd or not, what you guys have for tires, etc. too.