Been back and forth with a few different pipe combos- but the long story made short is that the 3" all the way back with the SW 3" X-Pipe makes great top end with plenty mid range torque using LS7 cats from a C6 Z06. It is faster than the stock mufflers on 2.7" pipe without cats. It's Freaking Loud, but then running stock muffs catless on longtube headers was a bit obnoxious too. There is drone, I will probably go to turbo mufflers again when I get some more money to spend. Additionally, I really like running catalysts again. Birds don't fall out of trees when you drive by, you don't get dirty looks from the beach hippy in a Prius, and it quiets things down and quells those decel backfires quite a bit. Lastly, I priced various aftermarket bullet cats with a 3" slip connect, but how can you beat factory Cats from a 505 hp car? You can tell it is running clean, the pipes aren't even blacked up yet and there is no odor at all. OEM parts FTW.
I had recently installed some LT5 headers and I found these 2" longtubes that were already setup for air injection. These aren't SW headers, but a mystery brand- maybe made by Morrison Motorsports in GA is the best guess I have so far. Anyhow, they fit perfectly and really woke up the car.
I was running cat-less for a couple of months after the header install (using stock mufflers), but I got tired of my eyes watering every time I pulled up to a stop light with my windows down. Since I had some oem LS7 exhaust that was a stillborn modification on my C6 that I decided to not go through with, I put those nice 3" piped cats to use. They are pretty compact and just fit under the heat shields in the tunnel.
