[NinjaBraap]

As a follow up now sometime later, here's what I've learned.

1. Yes, they're progressive but a much improved spring rate that works better for street/track use over previous generations. I'm riding A group at Buttonwillow on stock fork springs, but with 20wt oil and pre-load adjusters. (I weigh 145lbs currently)

2. For those with an R3 (don't witch hunt me Ninjette's lol, I own both currently) swapping in the springs and spacers from the N400 to the R3 vastly improves it's handling. Highly recommend on a budget.

3. Despite my friends winning amateur class championship and me riding A group on stock springs, I'm still opting to get a full set of cartridge inserts for full damping control, that will also be sprung to my weight and riding ability.

In short, TLDR, for 90% of Ninja / Z 400 Riders out there, even for the track, the stock springs will take you into racing just fine, but are still worth upgrading.