Emissions could be one reason. In the People's Republic of Connecticut for example the only way to guarantee that you'll bet through emissions is to have the stock cats in the stock locations, so the ability to swap the stockers back in can be important.The more appropriate question is:
Why would you attempt this setup?
For (one), you would be removing your stock shorty headers/manifolds anyway AND (two) for the price of BBK shorties, plus the MAK cat deletes you could just buy a set of non-catted headers (Pypes stepped headers would be my recommendation) which will give you equal or slightly better performance over the OP's original question, and wouldn't be any harder to install than the BBK shorties?
But I could be wrong.....
I might want to try anyway.
[MENTION=10868]AdrianMAK[/MENTION] is there a discount for forum members?