Dai Kaiju

I was browsing around for turbo upgrades and stumbled across the OBX twin manifold. This got me thinking about setups that could run twins. I've always been interested in the Holset builds I've seen but I've never seen anyone use them as twins and was wondering if they would be too big to fit, or if the 2.5 liters wasn't enough to spool them. If displacement is the issue, would this be solved by upgrading to the 1.5JZ?