The Manic Mechanic intake has a rubber seal which lines up with the black seal on the carb.
I tested 4 intakes, one was the stubby intake it came with, one was my favorite intake which is steel and a bit longer, one was aluminum, and the last was the MM intake. When I tested, I just did a blow test through the carb looking for leaks. The aluminum was terrible, as it doesn't go deep enough to make seal contact. The steel ones were better, but still had a major leak. The MM intake had ZERO air leak.
As well, I adjusted the float tang, changed the air filter cover, and chopped the choke cable.