A few weeks ago I bought my first "high-end" pen: a Lamy 2000. I got some Noodler's Heart of Darkness at the same time, so it was natural to use my fancy new ink with my fancy new pen. I fell in love instantly. The pen wrote fantastic and the ink looked spectacular.
About a week later, bitten by the Lamy+Noodler's bug, I bought a 14k nibbed Lamy Studio and a bottle of Noodler's Kiowa Pecan. Unfortunately, it was a big let down. The nib felt rough and was not pleasurable to write with. The color of the ink was fantastic, but I just wasn't having fun with my shiny new pen.
I was bummed out for a while until I finally decided on a whim to empty out the Studio and fill it with Heart of Darkness. What a revelation! This thing writes like butter now! Heart of Darkness is the miraculous pen-curing ink! To think, I had been toying with the idea of paying for a nib-smoothing when all I needed was an ink swap. I can't recommend Heart of Darkness highly enough.
Can anybody recommend any other inks that brought their pens to a new level of performance?