JBI WP Spring Perch

I’ve looked at it a bunch as well. Since it affects oil displacement outside the traditional valving from mid to end of suspension travel, I can see how it improves bottoming resistance. However I don’t see how it can improve plushness without a matching revalve to start, initial stroke valving would remain the same. 

JB is a good dude - maybe he’ll chime in here.

I haven't tried it on the forks you mentioned, but have it in both my KYB converted 4cs forks and the Showas on my RMZ 450.  I can't say I have absolutely noticed improvement on the initial part of the stroke being more plush, but definitely better on the bottoming resistance.  If you look at the design compared to a stock part, it makes a whole lot of sense.

Moved from spring perch to spring tube's on my Kyb Techncial Touch forks, and huge difference. Everything else was same. 

So a well tuned spring tube, with correct/adapted oil level can make a difference. I doubt WP spring tube leaves no room for improvement. 

They definitely worked well on the CC bladder forks for me. I could have bought brand new cones for what I put into those in revalves over the years 

Personally a big fan of what JB has done with the WP forks. 

I was out at Cahuilla and he let me try a sample set of forks with 6500 inserts, JB perches and JB valving. I compared those to my WP forks with "stock" 6500 kit as well as a set of CV's that were valved for my 350. I was trying these all on a new 24.5 KTM 450 (left the church, that's for another thread).

At the end of the day, I felt like JB's settings had the best balance of hold-up, plushness and bottoming resistance. Since then I have ridden Pala and Glen Helen as well as raced Mammoth. They have been some of the most "track toughness" forks I have had since my KYB A-Kit forks.

I am not sure how much the perches alone would give you initial plushness (maybe a little different feel based on the oil volume), but the overall setup/settings seems to be working pretty well.