With the right scoop the top mount is pretty efficent, and stealthy as all hell. I also ran my topmount almost all summer without a scoop, besides when NX-DET was nice enough to let me borrow his hood that has a scoop for the top mount. I ran the car all day at road america, 3 30min sessions a day, 2 days 80plus deg. each day. it worked well at 6psi.
The only thing to worry about with a fr. mount in a nx is cooling problems, your prob. gonna want to upgrade the radiator if your gonna get a large fr. mount, get better fans, and a nismo thermostat. Or vent the hood and make a cut of some sort between the headlights. That is if you like to beat on the car on hot days also, or if you do any roadracing or auto-x.
Later,Jon