there's different sizes available thomas. so called .63 is the biggest and presents less of a restriction to the exhaust gases so makes more power but is slower to spool up. below that is .43 and i think that there's another one. don't know what escos had. your one should be marked up with what it is anyway, and if you are happy with the response, get the same.

sorry, i wouldn't know where to buy it from.