Stage 2 has a little thicker element and will stick out from the back of the football, where the Stage 1 is flush with the back of the cover, if'n you use the stock air filter cover. Prolly will be more susceptible to water intrusion during a frog choking rain too.
Engine is only going to suck in as much air as it needs. Stage I is fine for stock. If you are going for a bigger build than a Stage II might be better.
$119.95 $96.40 no shipping cost!!! Save:20% off This is the price at eastern performance if you are looking. and i believe fuelmoto has good deals on them also. I just put on a se stage I ac. \
heres fuelmoto price
Arlen Ness Big Sucker Stage I $99.95
Arlen Ness kits include a Big Sucker aluminum backing plate, Team Ness High-Flow air filter, Chrome banjo bolts and simple instructions and all necessary hardware. This kit performs well, the filter element is a cleanable type.