So, I am finally wrapping up my ongoing motor swap in the near future. I have had the 2.5" exhaust out of my parts car for awhile now, still thinking of what to do. The exhaust is pretty rare. It is duals, but with no tips, because it came from a SE SC. I know some there are high hp Bonnies out there with the stock muffler. I really want a stock sound, but I want to cut down the KR.

My motor upon installation will have a 180* thermostat, PEMs, FWI, high flow cat, Autolite 104s. I have a MPS with a 3.4 and a 3.25, do you "think" I can run the 3.25 without a new muffler. Recently I bought two camaros, and one has a Flowmaster 80 series under it. I just don't know if I want to use it yet.

get some PEMS'* or a set of headers and a Highflow cat

There is no way you will be able to run a 3.2" pulley without knock with the mods listed above. If you add a DHP, 1:9.1 Rockers, 3" Downpipe, and 160* T-stat then maybe. Every car is different so start with a 3.4", work on running that pulley knock free and then go to a 3.3", etc. - work your way down. As for the exhaust start at the front of the car and work your way back. In order: Pems/Headers, 3" Downpipe, High Flow Cat/Offroad pipe, Res. delete, Muffler. The muffler will be the last thing (if ever) to restrict your exhaust.