yeah, the whistle comes around 1/3-1/2 throttle. s2 emailed me back today and said this,

So I read through some of those forums and the first two are from 2003 & 2004, which means those were the obsolete batch of manifolds, not the Pro Series, and the last 2 aren’t even about Skunk2 intake manifolds.
Unfortunately it is very difficult to trouble shoot a noise over the phone so my suggestion to you would be to either take the manifold to a professional and have them look at it, or double check all the vacuum lines because that’s what it sounds like to me. We have sold thousands of intake manifolds and have had no complaints about a whistling noise.

I then said this

Yeah, you probably wont hear any complaints due to the fact that people tend to either be quiet about these sorts of things or they live with it. From what I have gathered from a post I posted here, https://www.tamparacing.com/forums/h...whistling.html , people for some reason like the sound, they say it sounds like a blow off valve. I would just like to know if you all could test one or two out and find out where the whistle is coming from because would it not only make me happy, but it would probably make you all a little profit due to the ability to say "improved intake manifold; whistle free". Not only do I see your wholesale sales rising due to it, but bringing something up like this to your boss or something could throw you a few bills as well. The way these things sell and with the new competition from Edelbrock, fixing this problem will give you an upper hand. Or you all could not admit that there is a problem and when people like me come around, we can go and buy brand x that doesn't whistle and make our car look like a rice box. I know for sure the vacuum lines are all good and connected, they are all brand new. All seals are good and everything. The sound is coming from inside the plenum somewhere or the runners; I am not quite sure. But I would at least bring it up to your higher ups because I am sure they are all about business growth, no matter how they get there. Believe me, I am no retard and by the way the economy looks, I am sure your company is looking to get ahead. - Nick

Yeah, we'll see what they do about it. lol