It is not advisable to do many mods in regards to the engine as the X has a tendency to want to go into limp mode when you are flooring it around which is not an issue with the other Evo's. The "drive slow" light kicks in on the dash and that is the end of that until the transmission oils have had a chance to cool down
This is why I have suggested the minimal mods that I listed in my earlier reply.
There are more that can be done but why go too far when what I have suggested will give you sufficient power to put a smile on your face and get the engine performing to a reasonable degree.
PM me your reg and mobile number so that I can fill you in a little more.
It may be later on today or at some point tomorrow buddy as I am tied down with toooooo many parcels to get ready for despatch tomorrow. I am currently on number 17 of well over 90 items
El