Yeah, some trimming to the rear of the bumper and the centre and o/s vents. As long as you're careful with a dremel you'll be fine, it might even be worth picking up a bumper from a scrappy to practice on first. Make it fit then cut the real one.
It can be done for less by fitting a wellycooler but you'll end up with pipes hanging out of your vents. Like you I wanted mine to be completely hidden which is why I opted for this kit.
You'll certainly notice an improvement in the summer
