Does anyone make an ORY that bolts up to the stock exhaust systems?

 

I assume that is what would be needed for these if I want to retain the ability to replace the cats: http://www.jbaheaders.com/headerdeta...rtNum=1850-2JS

Also, I have seen shorties recommended for the Radix, but is the 1 5/8 tubing size adequate?

 

The shorties don't gain much power for you. Most people say the stock manifolds are just as good. I would go long tubes, or at least a good mid length.

 

If shorties are better than longs(I have been told) but no better than stock, I may as well use stock manifolds with an ORY. 90% of the restriction in the exhaust is in the cats anyway.

GM specs allow for a maximum catback back pressure of .5 psi (measuredat 2000 RPM).
Max allowed precat backpressure is 3 psi. It would appear that there is nothing else you can do with the exhaust that can equate to the improved flow of cat removal.

It would be nice to have a side by side dyno comparison of short/mids to long tubes on a Radix setup.

 

The shorties are not better than long tubes. The long tubes will yield more low and midrange torque and a horsepower increase throughout the rpm range. The shorties may show a slight gain in the upper rpm range only.

 

The physics of that make sense in normally aspirated applications but doesn't the supercharger change the whole equation? Todd@ProDyno says they consistently get their best numbers with short/mids with the Radix. Not sure what diameter pipes they are using.