Synchronizing PWMs

I am using the TIVA C (TM4C123GH6PM) launchpad, and I am trying to create 2 digital signals.  I need a 500kHz output with a 50% duty cycle, and a 25kHz output with a  20% duty cycle.  These signals need to be low jitter and synchronized so that the falling edge happens at the same time for both signals.  Here is what I have so far using the PWM modules, but I am unable to get the falling edges to line up.  I don't want the timing of these to be affected by other things going on in the processor, so that's why I picked PWMs.

#include <stdint.h>
#include <stdbool.h>
#include "inc/hw_gpio.h"
#include "inc/hw_types.h"
#include "inc/hw_memmap.h"
#include "driverlib/sysctl.h"
#include "driverlib/pin_map.h"
#include "driverlib/gpio.h"
#include "driverlib/pwm.h"

#define GPIO_PB6_M0PWM0         0x00011804
#define GPIO_PB7_M0PWM1         0x00011C04
#define GPIO_PB4_M0PWM2         0x00011004
#define GPIO_PB5_M0PWM3         0x00011404
#define GPIO_PE4_M0PWM4         0x00041004
#define GPIO_PE5_M0PWM5         0x00041404
#define GPIO_PF1_M1PWM5         0x00050405
#define GPIO_PF2_M1PWM6         0x00050805
#define GPIO_PF3_M1PWM7         0x00050C05

int
main(void)
{
    //Set the clock
    SysCtlClockSet(SYSCTL_SYSDIV_2_5|SYSCTL_USE_PLL|SYSCTL_XTAL_16MHZ|SYSCTL_OSC_INT);  // SET SYSTEM CLOCK FOR 80Mhz, off of PLL

    //Configure PWM Clock to match system
    SysCtlPWMClockSet(SYSCTL_PWMDIV_1);

    // Enable the peripherals used by this program.
    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOF);
    SysCtlPeripheralEnable(SYSCTL_PERIPH_PWM1);  //The Tiva Launchpad has two modules (0 and 1). Module 1 covers the LED pins

    //Configure PF1,PF2,PF3 Pins as PWM
    GPIOPinConfigure(GPIO_PF1_M1PWM5);
    GPIOPinConfigure(GPIO_PF2_M1PWM6);

    GPIOPinTypePWM(GPIO_PORTF_BASE, GPIO_PIN_1 | GPIO_PIN_2);

    //Configure PWM Options

    PWMGenConfigure(PWM1_BASE, PWM_GEN_2, PWM_GEN_MODE_UP_DOWN | PWM_GEN_MODE_NO_SYNC);
    PWMGenConfigure(PWM1_BASE, PWM_GEN_3, PWM_GEN_MODE_UP_DOWN | PWM_GEN_MODE_NO_SYNC);
    //Set the Period (expressed in clock ticks)
    PWMGenPeriodSet(PWM1_BASE, PWM_GEN_2, 160);
    PWMGenPeriodSet(PWM1_BASE, PWM_GEN_3, 3200);

    PWMPulseWidthSet(PWM1_BASE, PWM_OUT_5,80);  //set 50% duty cycle
    PWMPulseWidthSet(PWM1_BASE, PWM_OUT_6,2560); //set 20% duty cycle
    // Enable the PWM generator
    PWMGenEnable(PWM1_BASE, PWM_GEN_2);
    PWMGenEnable(PWM1_BASE, PWM_GEN_3);

    // Turn on the Output pins
    PWMOutputState(PWM1_BASE, PWM_OUT_5_BIT | PWM_OUT_6_BIT, true);

    //Do nothing (will handle other tasks later on)
    while(1);
}

Right now, the 25kHz falling edge happens .5us after the falling edge of the 500kHz.  Are there any suggestions on how to fix this?

Thanks.