I own this flugel. I updated the valve springs with OEM Yamaha valve springs, and I swapped the lead-pipe insert out with the OEM leadpipe insert for a Yamaha 631. I think the leadpipe insert helped a bit - it seems like the slotting is a bit better, but it wasn't bad to begin with. I felt that the valve springs were a little stiff though, and the softer OEM springs greatly improved the valve action. This horn plays a lot better than the amount of money I have into it. I'll never get good resale value out of it, but I don't really need to - I gig this horn using it to double for ballads, and for that, it's perfect.