Originally Posted by foibled
The restriction in the Razan/Nammor/Narbish hoses is in the acrylic tips. They come with holes ~9/32"-5/16" whereas the inner diameter of the hose is ~1/2". If you are handy with a drill, you can bore them out to improve the draw. Just be careful as the acrylic can crack/chip and the thicknesses at the thinnest points do vary from tip to tip. It's less likely to chip by drilling from both ends of each piece but getting the holes to line up in the middle requires careful and accurate drilling.
My Razan and one of my Narbish hoses have been bored out to ~13/32" at the thinnest point. IMO the improvement is very noticeable.
Strongly agree. The restriction is in the mouth tips. If you remove the mouth piece from a nammor or narbish and take a pull from just the handle, you will see a big increase in air flow.