This mod is CAT 3406E with straight pipe sound for SCS and modded trucks

Version 1.0 Feauture:
-CAT 3406E 475-625HP and 800HP Tuned engines with straight pipe sound
-Custom sound attenuation for realistic sound fade off and distortion effect
-Custom sound orientation for realistic sound from different angle
-Custom exhaust distortion for realistic exhaust tone depends on distance and throttle pressed
-Special variable exhaust tones
-Included Customizable Additional Supported Trucks (CAST) in the mod
If you don't know what CAST is :
https://steamcommunity.com/workshop/filedetails/discussion/665335536/3156453942274154402/

Quick tutorial on how to use CAST
1. Goto def/vehicle/truck/
2. Rename one of zcustom_xx into truck def name you want
(optional but should do)
3. get inside that folder/engine/
4. Open every c15a_xxx.sii files and look at line 3
5. change "3406e_xxx.custom.engine" to "3406e_xxx.(truck def name).engine" for every files in that folder
and you should good to go

Credits:
Slav Jerry - sound modding and samples
SCS Software - sound samples