I put an intake vane on my bst40 intake. It was nice. Mainly an improvement on 1/4 throttle. Then one day I gave it some good throttle and it sucked my vane loose. I had to stop and fish it out through the airbox. I used very thin brass for the vane and it caved due to the pressure.
Without the vane, I just couldn't ride the bike the same. I got used to creeping around turns, and without the vane I always felt like falling over. The off-idle torque was gone.
So instead of making a bigger/stronger vane, I ordered a pumper. I got an oversized 42mm since I plan on putting both intake and engine side vanes. So that should leave me with 40mm give or take and dual vanes. Sweet.