From a previous exhaust thread of mine:
"I lost a full 2 pounds of boost with this exhaust set up. I'm sure the 112lsa cam with 52* of overlap isn't helping. I have a 2.75" pulley and am only getting 7psi. I made 450hp/460tq today. These are the exact same numbers as before the long tubes and true dual. However, I'm making with it with 2 less pounds of boost. I guess I can either predict a cam swap in the future or just be happy with it for awhile. So same power, less stress on the engine, and $1000 lighter in the wallet..."

I went from 9psi to 7 psi but made the same power after a few tune tweaks. 2.5" true duals with Magnaflow cats and Magnaflow mufflers.

 

I would but they are really tore up. There i no flange or anything like when they were new. I wouldnt even sell em to someone they are so bad lol.

 

I'd like to see some dyno numbers myself. I can say that the quickest Radix SSS trucks all have long tubes including the quickest stock cam Radix truck.