On the exact filter that you built in the pics and the instructions, what is the rated CFM on it? I know the ones y9ou buy in the store are rated for specific CFMs. What size fan do you have on yours? Have you found that there are any issues when using the same size one for different cfms? i.e: If I use this on a 250 CFM fan, will there be a huge difference if i switch it to a 700cfm fan? Would I need to build a bigger one to accommodate the bigger fan? Also if so do you have stats on the different sizes of the filters with there respective CFM ratings? Sorry if this is to specific, just wondering...