The larger you go the greater lag you'll end up getting, if anything get the same capacity as the one you have but more efficient. The Vec C 2.0T uses the same inter cooler as the CDTi and the VXR so I dont think its a case of VX fitting an inferior one to none VXR's. Chances are that yours is the same as Matt's and easily good enough for your motor mate.
I would imagine the BSR map is made around the stock cooler as well, the BSR stage 3 for the NET only upgrades the downpipe map and injectors not the intercooler. notsure.gif