Advise/Pointers on enlarging hole in hood

cutting the braces is never a good thing , they are called braces for a reason and you just might go to close the hood one day and fold it in half if you cut through them , that said it looks like you could nibble another inch all the way round without getting into the angle part of the brace . That would get you up to a 12 incher . Just be sure you only cut the part way into the flat and keep away from the bend , Air nibblers is how I've always seen it done but the double thickness might be too much for them .