yellowbird1232

iTrader: (3)

Is there a noticable power difference if the cats are removed. Jet hot LT and Y pipe.

goinbroke

I had mac cats on mine. Took the cats off and picked up 20rwhp on the dyno. I would go with no cats.

cm02WS6

High flow cats such as Magnaflow/Carsound or Random Tech are known to dyno within 5 hp of an ORY.

Unforgiven1

iTrader: (5)

From what I can remember, MAC cats aren't very noted for their flow characteristics. So that's probably why you saw the 20rwhp.

There will definitely be a difference. Carsound cats are supposed to be the freest flowing cats. I say, if emissions is not an issue in your state/area take them off and just run an ORP.