Don't have to use the jig saw....I cut mine up with a 4 1/2 in angle grinder, with a cutting wheel. Trimmed the hole up with a grinding wheel, and it worked like a champ! (except for that big hole in my knuckle, but that's the result of a quick dumbass attack....)
Cut the holes small, you can always trim to make them bigger......
I love my vents...the only thing I woulda/shoulda done differently was mount them farther towards the front of the hood. I placed mine about 1.5 inch from the back of the hood, but then I had to cut into the rear hood cross-member......
Oh, and take off the hood. It's sooo much easier to cut when you don't have to worry about anything important underneath......With 2 ppl, it's a cinch to remove/reinstall the hood. and FYI....if you drop and and it latches, without the hood cables installed?? you can either trigger the release from underneath with a pair of vise-grips, or pull the headlight buckets out to remove the latches.....don't ask how I know