I always carry around a cellphone while racing and never had problems. I use the mx3 for racing and it has everything I need. I am actually one of the few that rarely glitch at my track.
1989 Mazda Rx7
greddy t04b, megasquirt ecu, PlX wideband, 12x28x3 fmic, 50mm hks clone wg, ssqv bov, Safc, ss oil lines, walbro fuel pump, tubo intake manifolds, ssac exhaust manifold, 3" dp, 550cc primary/720cc secondary injectors, etc.