Anyone use a K&N stubstack?

[68Formula]

I'm thinking I could use a little more cfm out of my 3310 for my 455. Supposedly these increase max airflow through the carb. Anyone that can confirm this due to direct experience?

[1969CamaroRS]

Actually seemed to restrict my airflow when I used it on my 14x3" air filter. When I would rev my motor up with the stub stack it would suck the entire air-cleaner assembly down so much it would block the throttle on the carb from closing (scary). With it off it didn't have that problem.

I measured I have enough space to run 4" high air filter, probably try it again with the 4" what it does, thou it makes me skeptical of seeing any improvement. I'll get my car tuned for the 3" and if it richens up the mixture (I the Fast wideband O2 sensors) I'll know it isn't helping.

[yellow heap]

I ran one on a 3310 holley-It did help mileage but never made it to the track though it did seem to climb in rpm's quicker after some minor jet work.

[notagn]

Substack might be good for the street or certian other conditions but it is a cirtian restriction for the top end.

[MonzaRacer]

Well used them for several cars, if you have choke housing on carb use it , and use as tall an air cleaner as possible.