increase reflexes, adrenaline boost, increase attribute (reaction), increase attribute (intuition), improved physical attribute (reaction), attribute boost (reaction) and suprathyroid gland all stack with each other (but increase reflexes does not stack with another increase reflexes spell). they all also stack with the reaction part of improved reflexes for everything except initiative.
wired reflexes and reaction enhancers both stack with each other, but only if both are wireless ON. They are both incompatible with everything else.
synaptic booster is incompatible with everything.