Mine is a 2003 K11 1.0 Tempest. I have added a cheap induction kit & lowered it by 35mm. in its current trim its revs out at 55mph in second & 81mph in third & 4th has never hit limiter yet! 5 th gear seem an overdrive gear and just comes into its own for cruising. check out a coilpack mod & see...
There's a 1.3GX in the yard which has 2 normal horns which may be better but my Tempest is fitted with 2 trumpet airhorns bought from Halfords a while back. Works great after we blew a fuse & upgraded from 10A to 15A. Loads louder.