moving your tach so you feel like you have a wrx is just rice if you ask me... that should be the last thing on your to do list if you are converting to a wrx... and to answer your original question about modding your current one instead of buying a new one... sure, go for it, its obviously possible to do because its its how its made in the wrx... frankly if you keep asking stupid questions you deserve stupid answers.

Try this method: attempt to do it... say you have done xyz and then you can say it worked perfectly check it it out blah blah... or say i have done xyz 'anybody else try this because after trying it didnt work for me'... you will get better results