I had to trim mine ( Active Power MK1 - twin nostril), more so down low where it got close to the radiator fans. I had built a simple fan box/shroud, so the fans were ~1/2" spaced from the radiator.
*FYI - I had noticed the nostril doesn't match up to the full depth of the radiator, as well that it leaves a good amount of the center of the radiator covered....I had thought about cutting it and redoing, to get more coverage and better cooling. I opted to leave it as-is...I have a 427 that makes ~600HP, and the cooling system has been more than enough (a good amount of stop & go in ~90F ambient, and 1 track day).