BHS
While it is typical for there to be a howl in that MPH range, you can make some improvements. The first year we owned the bike, I almost sold it because of belt howl. It just got louder as speed increased until your head would split open. Luckily you don't have that problem. I can only tell you what worked for me - your results may vary. And I might have to disagree with Mike about a couple things.
The second year, I got some help from an HVAC engineer who had a lot of experience with toothed belts - trying to keep them quiet on large AHUs. You notice that the tooth on our belt fully fills up the valley in the sprocket. The noses of the teeth are not bevelled or squared off and leave no air space. So, as our belt teeth enter the sprocket, the air that it displaces has to go someplace. The faster it turns, the higher the velocity and pressure and the louder it gets. It's the air that causes the howl....which is not the same noise as the squeal fixed by the grease. We're talking about a different noise.
So, what do we do about it? We leave some room for the air to escape. The belt clearance spec for our model year is 1 - 5mm. I have found nothing to explain the general urban legend on here that explains why people are always told to keep the belt as close as possible to the inner flange, even closer than 1mm. Maybe it's a holdover from the very early days before BRP redesigned the front sprocket. I don't know. So, based on this engineers suggestion, I moved my belt out to 3 - 4mm and the improvement was instantaneous. That's about in the center of the rear sprocket. 25,000 miles later, there is no abnormal wear on the belt, no chafing from the front sprocket, and just the hint of a noise between 42 and 45 MPH. I think that's there to stay.
About belt tension. Everytime I get the bike back from the dealer, they have the belt too tight. It's as if they've forgotten that the belt spec for 2008 - 2012 is lower than 2013. BajaRon has taken a lot of real world data with the cricket, especially in the 2008 - 2012 model year range - for both rear wheel elevated and rear wheel on the ground. Your value of 160# is a good value for wheel ON THE GROUND. With the wheel elevated, you might want to try to shoot for closer to 100#. Search the forum and you'll find a number of posts from him with all that data in there. I can't put my hands on an electronic copy at the moment, only a paper copy. I agree with Mike that keeping it on the loose side is a good idea, But I think the number you have is a bit high. You're probably over 200# with the wheel on the ground and I'd hate for you to lose your transmission output bearing.
And yeah, all this trial and error stuff involving the rear axle is a big pain. If you want to change it yourself, don't try to be overly precise with the belt tension or clearance spec. The axle always moves a bit as you tighten it. Be satisfied with a band.
I have a 2011 Spyder RT Limited with approx. 14K miles. Last Fall I had the rear tire replaced with an OEM tire. Soon after I started noticing a howling noise coming from the left rear of the bike that starts around 42 MPH, peaks at 45 and disappears again at 47. I disabled my after market belt tensioner so it is not the cause. I have approx. 1mm space between the belt and inner rear sprocket. I tried the grease mod on the belt sprocket but still no positive results. With the tire off the ground the belt tension measures 160 with a Cricket II. Should I try increasing or decreasing the belt tension? :dontknow:
I guess that I'm tone-deaf, and can't differentiate between a Squeal and a Howl... 
