Well you would need to know some tuning basics, or have a map made by people that have the same car... gladly there are a bunch of people out there....
There are sites such as
www.openecu.org that have programs that flash directly to the chip that is in your car through the OBD II port. All you would need is a Tactrix cable to do this, but somebody might have came up with an easier solution. What is good about this cable is that it is $200 and if you have a friend with a subaru or mitsu, you can tune their car for $200 and cover the cost of the cable easily.
http://www.piasiniengineering.it i think does Mazda 3 you should message him and ask, but if you do some forum research you should be able to figure it out easy enough from openecu.
if you have any other questions just let me know...