Yeah, I'm not expecting too much in HP gain if any, and I definitely hope to not see any decrease in HP or torque. My feeling is, yes the restriction, at lease while still new, isn't much at all, and because of this I don't see much if any back pressure created by the 3" long cat (there is only half the length of medium of the cat chamber with in it). If anything, I'm hoping for a bit more sound out the tail pipe with out having to modifying the muffler. I don't believe there is any chambering with in the pipe, i think what you are seeing inside are welds, otherwise it's smooth in there. The ID at the end of the cat chamber is 2.25" and from the header from the engine back to the beginning of the cat chamber appears to be darn close to 1 7/8" like you mentioned. The rest of the exhaust is not with me at the moment, so I can't comment on that. I'll get it back on in the morning when I get home from work and go for a spin and see what I've got.
