air filters and intake pipes

Hi, i ve heard from a couple of tunners that if you use an air filter you will gain HPs and if its larger its better. Or if you take out the air filter you will lose HPs. In my case i have the air filter directly to the throttle body in a box and a scoop on the hood, and i was told by a tunner that if i added a pice of pipe (2-3 inch long) air will gain velocity and engine will gain power. Does that make sense?

Depends.

Any air filter will add a restriction to the airflow, but the larger the better, within reason, as there will be less restriction. One big advantage, though, of the air being filtered is that it reduces engine wear and so power doesn't drop off as much over time - or suddenly if it swallows a stone, or somesuch.

That said, a well designed air filter assembly and air feed may feed the air to the engine more efficiently, offseting the slight restriction - this is a very big part in why almost every race car, with the exception of some 'drag' cars, is fitted with some form of air filtration

Not sure what the "tuner" means - perhaps the filter isn't as neat a fit as possible, and a short length of tube may assist the air flow from the filter to the throttle body?

Thanks for the reply!

My K&N air filter goes attached directly to the throttle body and its the correct size for it, and has a custom box so that air runs direct from the scoop, have a custom intake and ported head. It just makes no sense to me that he claimed that adding a pipe between the air filter and throttle body air well gain velocity.

Because from what i learn in the EFI Tuning Fundamentals course, i think my VE is good. From your answer, what i see is that he might be one of those "tuner" that make changes try and failure whith out going into the principals.