How much horsepower would I gain with all these parts together?

Hello. This is my first post as an FYI, I'm new. If someone already answered this question and I just couldn't find it please numb and I'll delet this, thank you for everyone's time. I have a 2003 Toyota Celica GT manual. I was wondering what the horsepower gains would be if I added a magna flow exhaust, DC sport headers, Throttel Body spacer, and a performance chip. I already have a Injen Cold Air Intake. If you think there are other parts worth getting or if I should buy from a different brand for a cheaper price I would appreciate that. But for the most part if anyone could give a good estimate on how much horsepower everything put together would give that would be great. Below are a few links to the parts I listed above, found at autoanything.com

http://m.autoanything.com/exhausts-mufflers/magnaflow-exhaust-systems

http://m.autoanything.com/exhausts-mufflers/dc-sports-headers

http://m.autoanything.com/air-Intakes/taylor-cable-helix-power-tower-throttle-body-spacer