adding a hood pin to my trunk trigger

Ideally, you should use a pair of diodes, one on the trunk wire, one on the hood wire, and then splice both of them together going into the alarm's brain.  That way, neither wire will ever "see" the other.

Diodes come in amp ratings, not ohms.  Since almost no power at all is being transmitted from the hoodpin to the alarm's brain, it really doesn't matter what rating you get, except that at some point, the diode is so tiny it's hard to work with.  A 1-amp is probably a good compromise between size and price.

If you didn't use any diodes at all, probably not much would happen.  But if you open your hood, the trunk light is also going to come on, and if you have an indicator on the dashboard to show the trunk is open, that will light up too...... it would be safer overall to use the diodes.

Don't forget that, of course, the diodes are directional--if you get it backwards it won't work at all.  I always forget which way does what, but all you have to do is hook them up just temporarily, and then test to make sure they work before you put everything back together.

just to add to what Chris said..... if the trunk is a negative trigger wire then I wouldn't bother placing a diode in place of the hood/trunk sense as it will not harm anything. If you are using a trunk wire that  outputs a (+) signal you will have to reverse the polarity of this wire and also place a diode on pin 30 of this relay.