Well I pretty much tried the same as you a few days ago and I'm also pretty sure that most people will tell you that you're better of with a 4" tube and filter. Check out this thread in I went through the same thing:

http://www.grandprixforums.net/f18/first-modification-25609-4.html

I took some videos of the final version and you can see them here:

http://www.grandprixforums.net/f18/cai-sound-when-cold-26274.html