This is an interesting topic. For a few years now I have given thought to developing an effective filter housed within the airhorn but like most "ideas" the demand is simply not there to support the development costs. I took a look at the individual filters by Roush - they are ugly like everything else that people put on these Webers/Injection units.
I ran my 48 IDA's with nothing and had no adverse effects but long term I wouldn't feel comfortable doing that. A Weber stack draws it's flow from the center and therefore makes it a challenge to design a semi-hiddin (non tumor like growth atop the beautiful stacks). It CAN be done and will be by someone with more money and time than most of us. Anyone looking to throw a 150K into development and sell these buggers for $30 a pop get in touch with me. You might have your investment back within 30 years.
