Well found a diagram of the cats off the workshop manual and emailed it to random technology... this is the response I got:

The diagram helps-- it pretty much tells us you'll need some universal fit converters. A direct fit replacement y-pipe, complete with converters, will run about $750. Tooling expense to be able to build it will be about $1,000. We can't justify that because we haven't had any demand for a replacement y-pipe.

Sounds like we are SOL on the aftermarket high flow cats?

-Dave