…according to Shiv from Vishnu Tuning: “today’s results show that a tuned Evo X (with no additional bolt-on parts) makes as much power to the wheels as a tuned Evo IX with a full exhaust” in this thread: http://forums.evolutionm.net/showthread.php?t=322616
Also, AMS has begun prototyping parts and echoed Shiv’s statements:
http://forums.evolutionm.net/showthread.php?t=322293 – Part One – Stock
http://forums.evolutionm.net/showthread.php?t=322326 – Part Two – Boost Control (they also test the flow of the Fuel pump)
Needless to say, it looks like the Evo X GSR is going to be quite tunable at least as long as we are talking the sub 400whp. Beyond that is still in the learning curve…