Agree with the comments on the catalytics. You will lose velocity and heat by keeping them. This will in turn make less power, spool slower, and once they blow up will destroy the turbo.
On a side note, that is the worst FMIC design I have ever seen. I thought the FMIC on the 350z JWT kits was bad, but this one takes the cake.
With the market fluded with nice fmic's (like the one linked below) why use something like that.
http://www.maperformance.com/product...stone_TRTT.jpg