i dont think it matters if its tapered or not, but from my understanding about the kkm, the inverted cone on the end causes turbulent air. the biggest filter ive known that will fit is a 9" K&N. The optimized TB includes replacing the stock throttle body plate screws with some flush mount screws or pop rivets. im not sure which one rick blackford uses. Also sanding down the TB plate to tapered edge for better airflow and sanding down the inside of the TB. Optimizing the secondaries pretty much includes the same thing.
