im not much of an engineer, but i made my own insert, it works great, heres how i did it. i looked at the plans for the gytr model, and it seems to me that it works by limiting the soundwaves exiting the pipe, hence the staggered lengths on the tubes inside. the tubes are too small to get a complete soundwave through. i took a piece of thinwall tube (1 1/2" long) that was as close as possible to the dimension of the inside of my pipe (i found a piece of what appeared to be conduit). then i took dimensions from the g-ytr insert for the tubes that go inside, i guessed that the geniuses that get paid for this stuff know what they are doing so i'd use their lengths, they were approx 4, 5, and 6" long. i took regular 1/2' conduit and realized that i could get four pieces of tube inside the main tube, instead of three, if i squashed them just a little. seemed to me that if i could get more tubes in while still reducing sound, i'd have to get better flow, and therefore better performance right?? so instead of the three tubes in the store bought version, i had one at 1" long, one at 3", one at 4" and the last at 5". i squashed them a little to get them to fit inside, and gas welded them in place, then i gas welded the gaps between the individual tubes so the escaping gases had to go down the tubes not past them. lastly i ground the end flat, put a small 45 degree corner around the end, welded a nut inside to accept a 10mm bolt to secure it in place, and sprayed it black. it works great. a huge difference in noise, but no major reduction in performance. (i realize that it has to change it some, but it seemed really good.) the gytr one looks cool, but part of its pretty demeanor is that huge plug of aluminum containing the tubes. if you did away with the aluminum, it seems to me that you have much more room for tubes to take gases out. and therefore a smaller reduction in performance compared to the yamaha version. sorry for the lack of pictures, i'm not much of a cyber nerd and have no idea of how to post pictures.