carb noise questions

[SFTorange]

Hi All,

The other day, I installed a Moroso 1" 4-hole carb spacer to try to solve my hot start problems (Edelbrock 1406). Everything seems to be working well, but there is a noticeable whistling noise that comes in only at a very certain level of throttle opening under load. My first thought was a leak somewhere, but I haven't been able to track anything down. I carefully retorqued the carb to make sure everything was even, and I have gaskets between everything.

Do these spacers just change the sound of air sucking through the carb?? The noise isn't all that bad, but I just want to make sure nothing's wrong. Any ideas?