Just to check
 

It is fine to run panel filter and turbo back decat system without remap?

panel filter.. probably yes.., full decat.. probably not advisable, potential to run lean + you wont benifit from fitting it as much as you should without mapping for it.

Depends very much on the model of the car as some are more tolerant then others to a decat.

It's an '05 blobeye wrx... Planning on remap soon but want to get a few more bits together like hybrid td04 injectors etc

You may find it will boost spike on the Newage with the decat.
This can cause detonation on the gear change or if you do a high gear slow pull through the revs i.e foot to the floor at 60-70mph in 4th/5th on motorway to pass a slower vehicle.
If you have a boost gauge keep an eye out for spikes and control your driving accordingly.
If you havn't a gauge then take it easy until checked or mapped (if needed).

I'll just stick with panel filter and back box till remap as don't wanna risk nowt :)