This is a very old issue that comes back every so often. For some reason, some people think they can out-brake factory ABS systems and there comes that thing about disabling the system while racing.
Here are the facts. A very good driver can out-brake a decent ABS system in very controlled and planed environment.
Some of the ABS systems that where shoving up lately here in the States (like f-body systems and so...) where not that good while racing and just because of the low quality of those, people think that is the case with all the others.
While racing, there is no way that you can control everything that you need to do and still take a perfect care of your brakes. And if you are left foot braker (as most of people driving turbo charged cars should), than things get even more difficult. Now, if we add the rain to the whole equation...
Good luck and keep those systems running and work an your skills with that system ON!
95 AWD #34 SM
"Let boost be with you...
...and bring some timing too!"