Maybe the car doesnt have exhaust pipe at all,but you can do a little trick to put muffler.
Open the rear bumper .cfg and add those 2 muffler slots
slot -0.451 -0.022 1.456 0.000 0.000 0.000 2 ; L muffler
attach 0x00040047 1
slot 0.450 -0.022 1.456 0.000 0.000 0.000 3 ; R muffler
attach 0x00040047 1
But you may need to adjust it in game so you gotta use adjustable scripts or move it from the cfg
Spoiler: # Vehicle importer wizard generated part configuration file #
resource ID of this part: 0x000000C2
resource alias of this part: "R bumper"
render 0x0000005C
mesh 0x0000005D
texture 0x00020025
click 0x00000103
body 0.000 -0.023 0.130 0.000 0.000 0.000 17.004 cars\racers\Duhen_data\meshes_phys_R_bumper_C.scx ;0x0000000C
body -0.796 -0.023 0.014 0.000 0.000 0.000 3.401 cars\racers\Duhen_data\meshes_phys_R_bumper_L.scx ;0x0000000E
body 0.796 -0.023 0.014 0.000 0.000 0.000 3.401 cars\racers\Duhen_data\meshes_phys_R_bumper_R.scx ;0x00000012
total mass: 23.806 kg
category 2
slot 0.000 0.208 0.205 0.000 0.000 0.000 9 ; R_bumper
attach 0x00000006 9 ; chassis->R_bumper
slot 0.000 -0.130 0.000 0.000 0.000 0.000 4 ; Neon
attach 0x0004D267 1
slot 0.000 0.050 0.250 0.000 0.030 0.000 10 ; Registration
attach 0x0004D326 1
attach 0x0004D331 1
slot -0.451 -0.022 1.456 0.000 0.000 0.000 2 ; L muffler
attach 0x00040047 1
slot 0.450 -0.022 1.456 0.000 0.000 0.000 3 ; R muffler
attach 0x00040047 1
'hatso lokharito' deflector
wing 4 0.000000000 -0.286399000 1.791210000 0.000000000 0.000000000 0.745803000 12.271920000 -0.250 0.666
eof