yeah, i have a ESR on the 86' and a FTZ on the hybrid, i didnt really notice a difference other than the nice o-ring non leaky seal. it depends on the pipe too, whether the head flange is on the loose end or not. but its def worth the money and they make your bike look better too. i like the ESR over the others because they mill around the spring holes so it looks contoured, idk.... but the FTZ was billet steel that was brazed toether, it definatley looks racy, but you need their billet pipe head flange to go with it, so its basically a racing only thing, and it uses double spring steel rings instead of orings...
1985 Honda ATC250R drag trike with s/t kit and full drag CR hybrid motor and drag chassis...
1986 Honda ATC250R daily rider fully modded engine, +4 swinger,etc...
1997 Polaris Storm 800 triple, boyesen reeds, dg individual silencers, 240 studs, 123mph on radar...