You won't be able to run water with the SPA manifold. Luckily its not really going to need it the way it's designed. You'll want the two manifolds to be as close as possible to keep the fuel from pooling.
Mine doesn't run well until warm because of fuel pooling. Even when it's hot out but not as bad then. I'm running water through my Offy intake tapped right into the water pump so it's circulating water as soon as the motor turns over. Even then it won't run well until the temp comes up to about 120 degrees. Until then it wants to stall.
I've never had my hands on an SPA manifold but I can't imagine it allows exhaust gases to circulate around the intake manifold like the stock one does. That would take away from boost and be a detriment. From the pics that I've seen it looks like it's designed to transfer heat through the top of the exhaust manifold through the bottom of the intake through convection. It'll probably take even longer to warm up than stock but if you're doing a turbo setup I'm guessing you don't care nearly as much. Even with an intercooler the charged gas is going to be warm enough to prevent pooling shortly after start-up anyway.
Long story short: logically you won't need water heat.
