The top grill is used a TON for cooling. With that blocked off just remember your fans; instead of getting cold air through the top of that radiator, will just be curculating the hot air in your engine bay which will be much less effective cooling wise and power wise.(a short ram intake would be a BAD idea) It looks Great, but there HAS to be a way to make it more functional, and Midway Garage right there on Division and 142nd could help you out with that i bet.
The Difference is all the cars you named are FAST and BEEFY, the focus (without some SERIOUSLY DEEP pockets) will never contend with any of them, and I hope they don't flame you for being slow but looking very awesome doing it lol. Even though with some upgrades you could be very fast among focus/cavalier/sunfire/ other 4 banger stuff its Just not in the same league as those guys. And will just be farther (power speed wise) if your cutting off a large port for cold air to get to the engine.
If its looks your after and your not worried about getting flamed, which is perfectly fine, then this bumper is tight and make sure your fans work lol.
Looking for: T4 57trim or larger Turbo, Wideband Gauge with wiring and sensor, HKS VPC with 550 chip