I've always liked my Noodler's Ahab pen that I have been using since around October, but I found its flexible capabilities to be a little lackluster. The nib always required a large amount of pressure to flex and would often railroad. Whenever I wanted to play around with flex, I found myself just picking up one of my vintage pens. The Ahab just wasn't worth it when it came to flex.
However, I had some free time the other day so I decided the Ahab would be worth messing around with since it was only a $20 pen. I ended up shaving off the shoulders of the nib with a dremel tool to increase it's flexibility and then I grounded the tip of the nib with some very fine grit sandpaper in order to enable it to achieve some nice hairlines. Then to fix the railroading problem I often encountered, I cut the channel in the feed deeper with my pocket knife. I also carved the fins in the side of the feed a little wider as well.
The result was really quite amazing. The nib flexed a lot easier and made thicker lines. It has only railroaded on me a couple times and that was when I was really pushing its limits. When it is unflexed, it makes some really nice hairlines and writes pretty smoothly to my surprise. I'll definitely be playing around with this pen a lot more than I have in the past.
Here's a few pictures I took. If anyone has any questions regarding this mod, feel free to let me know!