Ran mine under the tape too. Gave the cable/housing as much slack as I could between where they leave the bars near the stem and travel towards the downtube.

The cable/housing is from Porkchops, “vintage style.” I’ve never used it before, so I’m not sure what type of performance to expect from it. Also, never used barcons before, so once again, not sure what they’re “supposed” to feel like.

I did disassemble the levers first cleaning and lube prior to installing them.

That said, the shifters do feel tighter than any downtube shifter I’ve ever used. Takes a bit of force to move them, but not so much that I find it problematic. And like you, I have the friction adjustment set so that it’s as slack as can be while still holding it’s place in gear without slipping.