Thanks Rashid bhai you are correct.
I needed slightly bigger boot to accommodate pz30 carburetor. As I had swapped 200cc water cooled engine. But using some heat oil and force managed to fix existing one with pz30. Will route any one in need towards you.
What air filter setup are you using now?
I feel the stock boot pipe that connects the carb to air filter box is a bit restrictive.
Is there any other setup for air filter tested?