Air intake: under the hood or behind the grill?

[kikkegek]

I have been having some discussion lately and I was wondering what you guys think?

What would be the best place for air intake:
- under the hood (see my first picture)
or
- an intake behind the grill connected by a hose? (see second picture)





both pictures are from my car. The second is how I bought it, the first is after I had it fit with an LPG system. It now runs on liquid natural gas. which costs less than half the price of regular fuel. and we took 80% of the eco-stuf of the engine. No use for it in th Netherlands.

I think the intake like it was should be better:
1. because air from behind the grill is always cooler
2. less dirt/oil/etc from under the hood is sucked into the airfilter
3. works like a forced air intake on highway? => better performance? I think?

what do you think?