In my honest opinion, if you want to make a header that might command that kind of price, make one that is ST_ legal but still outperforms the Cobb/Brullen design. OBX copied it and is selling them for under $300 on ebay....but it uses a non stock catpipe and is not ST legal. TWE's designs are very good as well, but again, the cat is either not there or in the wrong spot. Anything thus far that keeps the OEM cat location, has been all but useless as far as gains.
I personally am not chained to having the stock cat location, and am very much interested in a no compromise design. However, I think that for that kind of cash....one design will not satisfy the different needs for different disiplines.