what is the preferred method of air intake on our cars. is it necessary to run an airbox? even if not using standard ecu. has anyone had any experience of dirt getting into engine through filter when ducted to nose cone? if so where is the best place to mount the filter? cheers

The absolute best is filters direct onto trumpets on throttle bodies. No restriction to speak of. Even better if you can stick the filters out of the bonnet for proper cold air feed.

Airboxes will cut down on induction roar though.

My car is rediculously quiet now its supercharged and I just put it down to no induction noise.

will the cold air feed be good enough so close to engine and heat?

I'm a great believer in a panel filter located within a suitable air box.

I'm not alone here.

SBD Airbox

If it helps, it also focuses the engine note.
This to me is a good thing.

this may sound like a daft question but why are some air filters facing backwards and some forwards? if the aim is to force cold air to the engine hen surely it should face forward as close as possible to a cold air feed?

humm sticking filters out of the bonnet is not best, sorry. The airflow across the filters changes with speed, you may have to put larger jets in the front facing carbs, not sure how you can minipulate with EFI.

You really need a non restrictive box so get even pressure across all inlets.

Regards Mark

its an intake to single circular inlet to t/b on f20c. would need to be a cone filter or a filter within a box!

How about a cone filter in the passenger foot well ? with a foot board in front of it

An airbox is the best method but its a real art to get correct. Sticking out in the air isn't the best method otherwise you'd see race cars everywhere with them..... obviously you dont!