I am sorry to bring this up again, but I couldn't find a dealer for the OC703, all they have is Owens Corning QuietR Duct Liner in my place, which has about the same NRC of the 703 and also pretty good in the 125-500Hz range.
The thing is they have it in 24kg/m3 versus OC703's 48kg/m3 density.
What should I do then? Put more sheets? Maybe 6" to compensate?