Help golfing MIPS assembly

Question

I want to write 7 assembly instructions (28 bytes) that runs a logical equivalent of this C snippet:

c = a + b + 6;
while (c > 5) {
  c = c - a;
  b = b + 1;
}

However, there are restrictions to the allowed instructions:

add, addi, sub, subi, slt, slti, bne

a, b, and c are located in registers $t0, $t1, and $s0 respectively. Assume they are declared as signed 32 bit integers. You may use other registers as necessary but you may not assume an initial value for any registers except $0 which is wired to ground (always 0, even if assigned to).

The best attempt to date is thanks to @Smac89 with the following assembly:

      addi $s1, $t0, 6     # d = a + 6
      add $s0, $s1, $t1    # c = d + b
loop: slti $t2, $s0, 6     # f = (c < 6) 
      bne $t2, $0, exit    # (c < 6) ? exit
      sub $s0, $s0, $t0    # c = c - a;
      addi $t1, $t1, 1     # b = b + 1;
      bne $s1, $t0, loop   # (d != a) ? loop; always true
exit: