St Croix website says they use Pac Bay Minima guides on that series rod, but they don't say if they're "micro guides" ..... just (lighter weight) non-ceramic ring guides.

I have the same problem with my ESP rods ... their micro guides won't allow much of a knot, or most bobber stops, to pass thru the tip guide without totally hanging up or causing a serious decrease in distance.

If I was using a knot that wouldn't pass thru the tip ... I'd opt for a different knot, rather than take the chance on changing the action of the rod by replacing the tip with a larger diameter one. Either that or go with no leader & tie direct, or switch the braid out for mono, copoly, or fluorocarbon line.