You may not have spike at all; it could be the way your tuner designed the boost mapping.
ECUTECK is good stuff they can ramp the boost up in the low to mid range and then taper it off as the revs climb for a safety factor. ANd of course they compensate for the increased boost with adjustments in the other areas IE fueling ignition etc. This may be what you have.
Was it dyno or road tuned? Or thru the mail?