I put in a 8.5 lbs fidanza in my b18b. I noticed a huge difference. The car runs alot easyer now. even going up hills with passangers the car seems to move alot more effortlessly. as for revving the engine at launch, ive noticed that yes i cant launch without stepping on the throttle. However reving it to 1100-1300 seems to be more than suffiicent to move the car without stalling it.
hope this helps