I have a 2 1/2" exhaust on the Super Roo. Existing manifold worked fine.
Here are a couple of links to YouTube videos, showing the car at idle, and under load.
idle Under Load As well as the 2 1/2" pipe, the car has a Magnaflow muffler and duel Magnaflow tips. The cat has been removed!
Since Rocketman swapped my cams last week with the Webs, the cars sound has become much deeper! I will re-record some video after the t-bird turbo goes on, as that will change the sound even more.
I'm really starting to love this car again!
--Russ