I've seen several Adapter plates welded directly on the HF/CX/STD manifolds. If your to lazy and really dont care about the setup sure do it. Just besure to put a nice fatty bead around the entire plate and mani a couple times. Also lots of heat helps the weld make penitration on the cast/mild steel combo.

 

word. I have mine welded on, its a temporary setup, and theres lots of fatty beads welded on there, looks like it will hold up until i build a new mani and go to a bigger turbo.