pse chart
http://www.pse-archery.com/cat.php?k=52357
there is a link on this page to it. at 27draw and 70lbs you are shooting the wronge arrow. last year i had a local dealer trying to sell some 200's for my buddies xforce. it was way under spined for 29 @70lbs. he even stated he could paper tune them.we took him up on his offer and watched him fail at it. but i can tell you one thing. 29 @70 with those arrows we did chrono it at 348. but that was dangerous and stupid. but i wasn't doing the shooting