The very first version of the firmware on the original xcelerion systems had some random braking problems. Sometimes it wouldnt have any and i had the smashed cars to prove !! I upgraded to version 2.0 last year and had zero problems after. This year ive bought a new speedo and it already has the version 2.0 installed, ill put the 3.0 version on when i get a minute latest is best in my opinion....
Steelie, why dont you try leaning your xcelerion out to slow it down ? Seems to work on your nitro cars
But seriously try altering your throttle limiter and motor timing that should work. If you get stuck i can forward you the profile from my rockcrawler which should be smooth......