My entry into the world of fountain pens was via
this exact kit. It came with a #5 fine IPG nib. I didn't know any better and used it happily as my only fountain pen for years.
Later in life I went pretty far down the rabbit hole on fountain pens (learning to do basic nib tuning and polishing, and amassing quite a collection of rather nice pens). One day I found this pen in a drawer, gave it a good cleaning, and inked it up. It was awful. Hard starting. Skippy. Not smooth, particularly scratchy in some directions. Dry. I couldn't believe I wrote with this pen for years.
But now I knew how to fix it. I disassembled the section, pulled out the nib and feed, deep cleaned everything, flossed the tines, spaced them out a hair to improve flow, re-aligned them (one tine was significantly higher than the other), and did a thorough polishing job with 12000 grit micromesh, then 0.3 and 0.1 micron mylar. The same treatment I'd given to most of my steel nibs, which never failed to significantly improve performance and make a nice writer. Under the loupe it looked good.
Though it fixed most of the directional scratchiness, the pen still just didn't feel smooth or nice to write with. It's been in the drawer ever since. I guess I got one of the regular old steel-tipped, low QC ones, I can only conclude that the tipping material (whatever it is) is inferior.
That pen is funny - it wasn't turned particularly well, I used friction polish which has long since gone dull, and all in all it was a good example of the kind of amateurish turning I was doing when I made it at age 16 or thereabouts. But the barrels are made of kingwood and have some excess diameter.
One of these days, I think it would be a fun project to strip it down, deep clean, re-turn to fix some of the geometry, do a good CA finish, and then put in a #5 Bock nib. Could be a really beautiful pen and a decent writer at that.