I have a blobeye wrx ej205 engine that is in need of a engine rebuild, would I be able to use the pistons from a bug/blob sti? Are they the same size or longer?

Cheers

 

just buy a set of forged ones that are suitable for your car as the forged are much better

 

Better depends on application. Plenty of sti's running around at high mileage with standard unopened engines at around 350hp (ie limit for oe turbo), so the piston are definitely good enough for that.

Having said that, OP, have you checked if you will require a rebore, because if you do you might as well get aftermarket pistons because the normal standard Sti pistons will not fit.

don't forget that you will also need new rings for used pistons, so the cost difference might not be that great, especially when you take into account the other costs of a rebuild (gaskets, bearings etc)