Glad you found this older thread Red ! Thx.
I installed a EK 530Z chain recently, didn't think to post about this upgrade.
The chain was more expensive than many parts I used in my facelift project. I purchased mine off eBay for $175 with free shipping.
Before I bought any chain, I read a lot about chains. The different ring shape types, tensile strength and chain pitch. My sprocket knowledge also was gained at that time.
For my project I stayed with the OEM pitch of 530, mainly because of wear and strength.
I also went -1 tooth on front sprocket and +2 teeth on rear sprocket in this project, I didn't want a reliability issue with the "added" acceleration using a weaker 520 pitch chain.
I didn't have or I didn't notice vibration from the OEM chain. And don't notice any now with the EK chain.
My Busa was always smooth, though there was a slight "build up" time from about 4 to 10 mph. Now there is none; it's all go when the clutch lever is released.
I did add the "clutch lock ring kit" from Carpenter during this project.
I'm sure the "added" acceleration is a collaborative effort of all the updates.
The EK 530Z chain handles the Busa's power effortlessly. No hassles, no issues, no problems. It's direct power, at the twist of the throttle.
It's like riding a electric bike, instant acceleration.
Now, with the chain and other doodads, I run out of riding skill faster than before. Much faster !!