K&N myth?

[General Baxter]

is it a myth or not?

if you just bolt on a K&N to a carb car (no other mods)
do you have to rejet it?

[snapper]

Well I guess you don't have to, but it would definetly be beneficial. You're getting more air in due to having a larger filter area exposed so the extra fuel from larger jets would keep the mixture correct. Either change the air jets for smaller or main jets for slightly larger ones (eg. 165 to 175). You'll find the car pulls better up at the top of the rev range.

[Snowface]

in 99% of case it won't matter if you re-jet or not i think.

if you could step up single digits (like dellorto jets) then maybe it might be worth it.

But going from a 175 to a 180 main is way too much for just adding a K&N air filter.