in the last week and a half i switched from hooker 1 3/4 inch supercomp long tubes w/ d-port, to hedman longtubes w/ 1 5/8 primaries, and redid my y-pipe with the same 2.5" tubing into a 3" to dynomax ultra flow single 3" in/out. The hedmans were a B&#*h to get to fit in the car, grinding the k-member and a arm, and putting small dents in the primaries, installing an o2 bung, also, since i have d-port heads (l98 corvette) i had to file the round hedmans to match. the passenger hedman went in NO problem at all, and the hokers went in out super easy, (t56 so no engine jacking ). both with open headers, the hedmans are quiter, not by much, but you can notice it. running headers only, the headmans clearly have more low end torque, and i did not notice a top end power loss (HSR on a zz4 from gmpp). switching from the two highflow cats and stupid looking y pipe to no cats and linear y-pipe allows the engine to revmuch faster, and makes taking off from a light sooo much easyer another positve about the hedmans is that they have 1.5 inches more ground clearance, and have the ball and socket, vs the 3 bolt flange on the hookers. i kno that for a wild motor, the hookers would be more effective, but for a mild motor, the headmans seem like the way to go if you have the time (and not the money ) i will post befor and after pics of my y-pipe whenever i get them on the computer