Ok, I see where you coming from now.
You should update what cars you have under your avatar But yeah, I see it in your signature.
So really, all you have is an EVO to get around in.
If so then I would leave it stock, cruise around with it until you are ready for the R34 GTR, in which you said late next year.
If you feel the need for a bit more power / more exciting daily: Just upgrade the basics.
Change the panel filter to a high flow one and find a decent aftermarket exhaust.
If you want to roll around in style, get a set of coilovers and wheels.
Then just return it back to stock when selling it.