i dont mean to nag at you but i just took a look at the DNX website. I would compair these to the mufflers they sell on ebay for like $70 this is just me talking, but i wouldnt put that one a 97 civic with a b18c1 swap

and yes i do see there dyno charts, Remeber that that is about $1,000+ they spent on the car, and it only makes 9 more horses

This is the only thread on honda-tech about them, sorry it does not help that much
http://honda-tech.com/zerothread?id=649714