Before I got the Volant, I ran a K&N drop-in replacement filter in the stock airbox. There is an 'elbow' inside the box that goes to the fenderwell for air and a lot of people are cutting that off flush with the inlet to the box on the interior. It provides a bit less torturous path for the air to flow. I swapped in between the stock paper air filter and the K&N a while back at the track and the runs were identical. No gains. The Volant was worth 0.1-0.15 sec over the stock airbox and K&N drop-in for me with the reso delete and the Banks.