I already have a motordyne Spacer con my Vq35de, but im planning to buy the Kintetix racing V+ plenum for heat control purposes. This can be installed with the motordyne spacer or i have to use the Stock plenum gasket in this case?

 

The kinetix bolts straight to the manifold. The plenum is completely gone from the equation. So, no, there would be no place to put it.

The kinetix is for FI applications tho, and you would actually be losing power vs just doing the spacer/aramid gasket combo. I'm not sure what kind of cooling you're talking about, but the Plenum spacer/aramid gasket combo keeps your intake plenum much cooler than stock.