[Andy Barwick]

Dalola,

Having seen the photo's of your filter installation, I anm convinced that you will have considerably reduced any benefit that would be gained by fitting the K/N stub stack.
The stubstack is shaped to allow the air to be pulled in from over the sides of the inlet as well as down the middle, I.E. the large edge radius allows air to be sucked in from an angle up to 180 degrees from the vertical!
This is why, if a filter is installed over a stub stack, there must be sufficient free air space left at the sides and above the stub stack to allow the air to turn into the inlet.

Quote from K&N expert:
"The K&N Stubstack reduces turbulence, improves metering accuracy and increases the airflow by reducing restriction while straightening and speeding up air-flow. The Stubstack was designed to increase the airflow of carburetors by decreasing the restriction AROUND the choke horn. It fits inside the air cleaner housing and slides snugly down over the choke horn"

Also your home made filter will stop nothing apart from rocks.

good luck

Andy