Originally Posted by GUTCH
Any insight as to what flashing and mapping is?
Flashing refers to the actual writing of data (your ecu tune) to the EEPROM (electronically erasable programmable read only memory) in the ECU. It's basically a memory chip in the ecu that is normally only readable, but can be overwritten entirely with new data. ( you normally dont want your cars ecu data to change, right? =] )
A map in the ECU is basically a big lookup table that looks like a grid, the ecu uses vehicle sensor inputs (such as RPM, TPS, Coolant Temp etc.) in order to determine the proper output of the specific map. ECU maps can control several things such as timing, AFR, Engine Idle (warmup), Boost etc.
Here is an example of a Boost map in a subaru ECU that uses throttle % and RPM to determine the appropriate amount of boost to allow.
And here is a map from Nistune (awesome program I used to use on my SR20DET) where the user is tuning a desired AFR