Contour Enthusiasts Group Archives Forums Modifications Duratec Performance magnaflow cat

I'm getting the MSDS headers and y pipe and wanted to know what the right size would be for a high flow cat between 21/4 and 3 in. I have 21/4 bassani catback on.

From past experience I would recommend getting the cat made for the size pipe you are running. I had a set up that stepped up to a 3" and back down to 2.25 and it seemed to cause a restriction. My best guess is that the larger cat slowed the velocity of exhaust gases and caused the restriction. I started running without it and gained 10hp.

Do any of these 'hi-flo' cats have small cell density (less cells per sq inch) than the stock 'brick' or is it a standard brick with a bigger inlet & outlet ?..