Different spool rates with MBCs? wtf

[Kougar]

This has bothered me since I swapped my MBC a few weeks back. I have 2 boost controllers: 1) Turbo XS MBC, and 2) Homemade one.

Here's the deal. When I put the Turbo XS one in (set to 10psi), my spool seems rather slow, and i swear to god it muffles the sound of the turbo itself. With my homemade one (used to be set to 16, but now it doesn't really have a ceiling) you can hear the turbo spool loud, and boost comes on FAST. I'm monitoring all this through an autometer boost gauge.

What gives?