Id make a flange like mine, and use 2 high flows, I gave you links for ones for like 30 something bucks. Of cut the flange off of the stock y pipe and then put the 2 cats on there. Either or.

 

what if i cut off the flange, and found an adapter to go from two 2.5 inch (are the stock pipes 2.5 inch?) down to one 2.5 inch pipe and just clamped this on and clamped on a 2.5in cat. would a parts store carry such an adapter

 

Redcoat, my exhaust follows a standard path out where the stock one went. You can buy new pipes at a NAPA (buying a pipe expander makes it easier once you are putting it together). And if your truck has rust underneath, save yourself a headache and buy new hangers too.

 

I used the universal heavy duty hangers, the stock pipes are 2.25 so you will need an adaptor for the 2.5 cats if you cut the flange off, or if you make the flange like mine then just use 2.5 pipes.

 

Do the aftermarket "universal" "high flow" catalytic converters hold up as well as the OEM-type? They seem quite a bit smaller; seems like they'd either overheat quicker under load...or not have the capacity to clean the exhaust as well as the original type?