Hey guy's if any of you are looking at buying 4 stroke pipes you may want to pick up the latest issue of dirtbike. They tested all the big name pipes on a yz-426. althought its not a 4 wheeler engine it does show the dyno runs for each pipe, I was suprised to see some pipes faired well while others like the supertrapp were given a c- the best pipe was the yoshimura A, then the procircuit t-4 A-, and the almighty e-series a B. Its just a suggestion if you want to see how the pipes really stack up.