It's not going to happen unless you slap together a turbo setup or just run a decent shot of nitrous. A nitrous kit is around $1k and most will add up to 150 hp, which is more than N/A can probably take without other modifications. From my own experience here's my opinion on your potential mods:

Headers - not going to add what you are looking for..will be much louder, but without a cam or some method of improving flow internally probably won't do much.
Gears - no.. makes every gear shorter, the N/A's 0-60 numbers are low due to early shift points IMO.
Injectors, MAF, TB - not going to add power, just change throttle charicteristics.
ECU tune - will add some power, but not what you are looking for.
Cam - where are you getting one? I would imagine little to no gain unless you threw alot of lift and duration at it, punched out the heads and then got the headers.. then you lose vaccuum and drivability. My guess would be 300-315 with a bigger cam, headers and mild headwork.

The only way to keep up with a forced induction version of the same car is to add forced induction as far as I am concerned. Raising compression, a big cam and headwork are the traditional N/A mods, but if you want to run on