Originally Posted by dsm94
i wouldnt run off wg pressure. Too many people blow there motors doing that.
At this point the OP needs to clarify what he means by "spiking." To me, it sounds like the wastegate is not opening, boost is "spiking" up quickly. If he runs wastegate pressure (~10psi) and verifies that it is holding steady, then we can rule out the wastegate not opening properly and pin it on the mbc. Of course if it's creeping (what liquid suspects), then that is a different story...
OP, to run wastegate pressure run a vacuum line from the turbo compressor (or jpipe) straight to the wastegate actuator. This will essentially bypass your mbc altogether.