i went from a 96 civic ex, where i could shift at approx 2900 RPM into the next synchronized gear without a single jerk (very smooth). however, does anyone know the same exact shift point in a 98 prelude S?? i have a feeling its around 3400 rpm but it doesn't always work in it.

Also, has anyone removed their stock air filter and put a K&N in? worth it?

 

Could you not just take it out drive it and find out for yourself.

 

it will be different in each gear, and depends on how fast you shift...

 

yes, people have removed their stock airbox's and stuck in k&n filters. improved throttle repsonse and low end torque? maybe worth it, maybe not