I like the .48ar personally for your app, if you ever did decide thath the turbo was sufficient i dont think that just having the .63ar would support the extra hp you would want to make anyways. So for your current setup and current goals the .48ar would seem to fit you better.

As said above if you swap and want more power you will want the .63ar...But i think if you really wanted more power you would need to upgrade the turbo regardless, hence my thoughts on the .48ar

and also i like the greddy profec b spec II also, not from experience yet although i have heard great things and the price for that EBC is pretty damn good!