sorry dude but that 4 banger wont get any more faster even with Exhaust, Cold air intake, headers, cams, and a new PCM. all those things will make ur car haul a$$. but the 4 banger wont get sh#$t with the parts and will make it sound really gay. what i suggest is that you can sell it for about 2k and get a pretty good GTP Grand prix for a good low price or a G6 GTP or GT. those are fast and the GTP Grand prix is SUPERCHARGED which means more hauling ass and all these parts i listed put them on and ur car can beat the living daylights out of a Charger and Challenger R/T, or even the Mustang GTs. other than that get something like the trans am or something. bottom line the 4 Cylinder wont get that much HP because of how much low power it has. sorry dude but you will have the Need for speed in the GTP or trans am or even the G6 or G8 for sure. the base G8 is fast and can go faster. Hope i helped, and oh ya find a supercharger for the sunfire, u might have a chance to make a custom one which will cost a whole lot but can make ur sunfire haul ass since its super light.