downpipe with magnaflow/stock main cat?
 

Does anyone know of a downpipe or pre-cat delete that is compatible with the stock OEM main cat or the Magnaflow replacement?

all of the JDM ones will, they didn't have a separate pre-cat/connecting pipe thing like we had.

the RB 2.5" one can be made to fit, it needs to be cut and have a 2" or so piece of pipe welded in. or you could buy a pair of flanges, and make a short pipe.

I'll need to keep note of that in the future. But I've always wondered why RB decided to have such an awkward length for their downpipe. Was it just to make people by the whole turboback?

Rotary Performance has TII downpipe that bolts to factory/replcement cat

Yeah stumbled upon that one, looks like A'pexi also offers one as well.

A 3" flange will bolt to a stock 2.5" flange if you use an intermediate-sized metal-ringed gasket.

I used a Vibrant 1465 (2.75") to bolt a 3" midpipe to the stock y-pipe, with good sealing. You could similarly use the gasket to bolt a 3" downpipe to the stock main cat.

Another part like this (3" diameter, but stock fitment) is the Corksport downpipe, though it is out of production.