Originally Posted by Knot 4 Me (Post 4600389)

Call and talk to Dustin at Whipple. My guess is he will want you to remove the CAT's and go with aftermarket manifolds or headers. By the time you purchase those and possibly have to have tails made along with the price of the reflashes you are probably better off building 383's. You will have a ton invested in those stock 6.2's with probably less than desirable results and still have weak links in the engines.

Originally Posted by Keith Atlanta (Post 4600699)

Whipple did the 8.3 with Cat and sensor.
https://www.offshoreonly.com/forums/...2-engines.html

I dont know why they dont take the Cats out - maybe a machine shop could put them in a fixture and get them out with a Bridgeport or similar.

But the root of the question is Whipple did do it on an engine with Cats....