viper 690xv, '95 mustang

I recently purchesed a viper 690xv to install in my '95 mustang. Since I am a newbie in alarm installs I have a few simple questions.  I would also like to mention that i have read (and re-read) the directions and searched for posts relating to these questions. 

I understand that the horn honk feature pulses my existing horn.  I also understand that i can turn my 6 tone siren (from viper) into a single tone, so can an I have the horn honk feature pulse my siren?  Would it be lound like my horn?  I am asking this because i also want to get a piezo siren and figured it would be easier to hook up this way.  Also, if i am using only one piezo siren would I need a relay since it uses much less power?  Has anyone had experience with the DEI 513T mini piezo speaker, and if so, is it loud enough to be a pain generator?  Would two cause more "pain"?

I would like to thank everyone for their input, i have learned a lot on this website by reading many, many posts.

Brian