That conversion is not correct
This is what a automotive Vacuum gauge would read
Default MAP kPa to inHg (vacuum gauge) to PSIG
105 kPa = +1.48 inHg = +0.72 psig
104 kPa = +1.18 inHg = +0.58 psig
103 kPa = +0.89 inHg = +0.43 psig
102 kPa = +0.59 inHg = +0.29 psig
101 kPa = +0.30 inHg = +0.14 psig
100 kPa = -0.0 inHg = -0.00 psig
99 kPa = -0.30 inHg = -0.14 psig
98 kPa = -0.59 inHg = -0.29 psig
97 kPa = -0.89 inHg = -0.43 psig
96 kPa = -1.18 inHg = -0.58 psig
95 kPa = -1.48 inHg = -0.72 psig
94 kPa = -1.78 inHg = -0.87 psig
93 kPa = -2.07 inHg = -1.01 psig
92 kPa = -2.37 inHg = -1.16 psig
91 kPa = -2.66 inHg = -1.30 psig
90 kPa = -2.96 inHg = -1.45 psig
89 kPa = -3.26 inHg = -1.59 psig
88 kPa = -3.55 inHg = -1.74 psig
87 kPa = -3.85 inHg = -1.88 psig
86 kPa = -4.14 inHg = -2.03 psig
85 kPa = -4.44 inHg = -2.17 psig
84 kPa = -4.73 inHg = -2.32 psig
83 kPa = -5.03 inHg = -2.46 psig
82 kPa = -5.33 inHg = -2.61 psig
81 kPa = -5.62 inHg = -2.75 psig
80 kPa = -5.92 inHg = -2.90 psig
79 kPa = -6.22 inHg = -3.04 psig
78 kPa = -6.51 inHg = -3.19 psig
77 kPa = -6.81 inHg = -3.33 psig
76 kPa = -7.11 inHg = -3.48 psig
75 kPa = -7.40 inHg = -3.62 psig
74 kPa = -7.70 inHg = -3.77 psig
73 kPa = -7.99 inHg = -3.91 psig
72 kPa = -8.29 inHg = -4.06 psig
71 kPa = -8.59 inHg = -4.20 psig
70 kPa = -8.88 inHg = -4.35 psig
69 kPa = -9.18 inHg = -4.49 psig
68 kPa = -9.47 inHg = -4.64 psig
67 kPa = -9.77 inHg = -4.78 psig
66 kPa = -10.07 inHg = -4.93 psig
65 kPa = -10.36 inHg = -5.07 psig
64 kPa = -10.66 inHg = -5.22 psig
63 kPa = -10.96 inHg = -5.36 psig
62 kPa = -11.25 inHg = -5.51 psig
61 kPa = -11.55 inHg = -5.65 psig
60 kPa = -11.84 inHg = -5.80 psig
59 kPa = -12.14 inHg = -5.94 psig
58 kPa = -12.44 inHg = -6.09 psig
57 kPa = -12.73 inHg = -6.23 psig
56 kPa = -13.03 inHg = -6.38 psig
55 kPa = -13.32 inHg = -6.52 psig
54 kPa = -13.62 inHg = -6.67 psig
53 kPa = -13.92 inHg = -6.81 psig
52 kPa = -14.21 inHg = -6.96 psig
51 kPa = -14.51 inHg = -7.10 psig
50 kPa = -14.80 inHg = -7.25 psig
49 kPa = -15.10 inHg = -7.39 psig
48 kPa = -15.40 inHg = -7.54 psig
47 kPa = -15.70 inHg = -7.68 psig
46 kPa = -15.99 inHg = -7.83 psig
45 kPa = -16.28 inHg = -7.97 psig
44 kPa = -16.58 inHg = -8.12 psig
43 kPa = -16.88 inHg = -8.26 psig
42 kPa = -17.17 inHg = -8.41 psig
41 kPa = -17.47 inHg = -8.55 psig
40 kPa = -17.77 inHg = -8.70 psig
39 kPa = -18.06 inHg = -8.84 psig
38 kPa = -18.36 inHg = -8.99 psig
37 kPa = -18.65 inHg = -9.13 psig
36 kPa = -18.95 inHg = -9.28 psig
35 kPa = -19.25 inHg = -9.42 psig
34 kPa = -19.54 inHg = -9.57 psig
33 kPa = -19.84 inHg = -9.71 psig
32 kPa = -20.13 inHg = -9.86 psig
31 kPa = -20.43 inHg = -10.00 psig
30 kPa = -20.73 inHg = -10.15 psig
29 kPa = -21.02 inHg = -10.29 psig
28 kPa = -21.32 inHg = -10.44 psig
27 kPa = -21.61 inHg = -10.58 psig
26 kPa = -21.91 inHg = -10.73 psig
25 kPa = -22.21 inHg = -10.87 psig
24 kPa = -22.50 inHg = -11.02 psig
23 kPa = -22.80 inHg = -11.16 psig
22 kPa = -23.09 inHg = -11.31 psig
21 kPa = -23.39 inHg = -11.45 psig
20 kPa = -23.69 inHg = -11.60 psig
19 kPa = -23.98 inHg = -11.74 psig
18 kPa = -24.28 inHg = -11.89 psig
17 kPa = -24.58 inHg = -12.03 psig
16 kPa = -24.87 inHg = -12.18 psig
15 kPa = -25.17 inHg = -12.32 psig
14 kPa = -25.46 inHg = -12.47 psig
13 kPa = -25.76 inHg = -12.61 psig
12 kPa = -26.06 inHg = -12.76 psig
11 kPa = -26.35 inHg = -12.90 psig
10 kPa = -26.65 inHg = -13.05 psig
9 kPa = -26.94 inHg = -13.19 psig
8 kPa = -27.24 inHg = -13.34 psig
7 kPa = -27.54 inHg = -13.48 psig
6 kPa = -27.83 inHg = -13.63 psig
5 kPa = -28.13 inHg = -13.77 psig
4 kPa = -28.42 inHg = -13.92 psig
3 kPa = -28.72 inHg = -14.06 psig
2 kPa = -29.02 inHg = -14.21 psig
1 kPa = -29.31 inHg = -14.35 psig
0 kPa = -29.61 inHg = -14.50 psig
