I first ordered the SLP loudmouth (from mustang tuning.com) and when I opened the box I started laughing about the loud sound I will produce, finally and before installation, I changed my mind and exchange them for SLP powerflow, the same design but with a little muffler "around" the exhaust tubing.
I think I was very right to do this, because it is loud enough with those, I cannot imagine with the loud mouth !!!
I also have a "drone" but at lower rpm, 1500 ? I didn't really paid attention, but I try to avoid it by changing my trhottle angle.
just to mention : I was glad mustang tuning exchanged me the exhaust without any problem, altough it was impossible to get in touch with them over the phone (I first was afraid not to get in touch with them) they deal with everything by email.