If you are shooting the Drenalin with 80% let off your spine should be ok with any of those arrows up to 70 lbs. You may want to use a wrap though to stiffen the spine a little. Try to remember when looking at this that the spine is probably a little stiffer than what is shown. The program uses IBO speed and every bow's IBO differs depending on DL and the actual performance of the bow. Your bow's IBO will not be 320 FPS as listed by manufacturer because that IBO is for a 30" draw length unless otherwise specified.

You need the speed of a known arrow shot from your bow to adjust theIBO speed for your bow and a program like Archer's Advantage to figure out the exact spine. OT2 does not compensate for slower IBO's. So, ifthe program showsthe spine on the low side it is probably actually in the middle or slightly high. I've used this method with this program and have no issues with my arrows.