i do not have a whipple but i do run a procharger, i use a gaffrig boost gauge and i too have noticed that sometimes it reads different under the same conditions and rpm. i never know if i am really getting more boost, or if my gauge is screwed up. i seem to be going about the same speed when it reads 5 lbs as 8lbs( that it reads every now and then) i do not know if this helps at all, but i thought i would share my experance. good luck