First off.
A) I'm not completely sure "The Fatty" JFab is referring to have tried has anything to do with an exhaust on a motorcycle.
He has exhibited Wise-N- Heimer tendencies in the past... Shame on you...
B) I know... "I didn't inhale"... I'm sorry, I'm only Human, I did...That was along time ago...
O.K. .. Shame on Me... This was a test, back to business.
C) Pro Circuit- Works & Platinum have the same cone design, different finish
"Increased horsepower and torque gains will quickly be noticed across the entire rpm range."
http://procircuit.com/support.htm Jetting chart,etc..
D) FMF -
http://www.fmfracing.com/Mode/Category/51 This link should go to their site and explain their design intentions.
jetting charts
http://www.fmfracing.com/TechSupport/JettingCenter Tuck\o/