These are best used on the 30mm and 32mm manual choke carb kit offered for 250cc scooter, if you are using a 170cc or larger kit thi sis the manifold to use. I do modify these for my own use by taking the ridge out so carbs fit much better, I can do this for you if you ask and tell me what carb you are using.
Teflon Coated Manifold for GY6 150 to install 30/32mm carbs
this manifold is the short style for hard to reach carbs and intakes due to space when dealing with that bar that crosses over engine.
Stock intakes seem to wear and basically dry rot and start leaking air, adding this intake solves that problem.