I saw the topic about mystery mod had been revealed, and they said it's an intake mod and something to do with resonance.. Anyways, did you guys ever heard of Spoon Ventuli plate?http://www.inlinefour.com/spoonvenplat.html . I think it's same thing as this set up

 

I thought you misspelled "venturi" until I pulled up their site. I noticed they said nothing about top end. IMHO, it seems that something like this would actually restrict airflow and hurt top end. It looks like a way to match port the intake/head without cutting.

Pretty interesting.