go to rsr.com and it says for the gst is is 70mm= 2.75in, the gsx is 80mm, 3here's the link: http://www.rs-r.com/exmag.htmthey have some nice pics of it too! i think i might get this. if any of you guys do, then post some pics of it on an eclipse.-------jezreelhrc stage 1, sfmu, ml, prokits, egt, boost gauge, apexi tt, costum dp, dynotune fp gauge. gst muff, turbo spoilernothing like driving with the windows down and the music low: i love hearing the turbo spool, swwwhhhttt!!!!