Hey GP_maniac... i had to teach myself this one cause i was too old to understand the toots...
Decide on a car and get a 2014 sounds from the "gp4 sounds" archive, or you might have your own---
Next you will need the sample editor 1.6---from realgpx
heresa normal readme---give it a try---remember to point the editor to your "game_snd.bnk file
Installation
************
Extract the contents of the rar file in a temporary folder.
Open Samples Editor (Get it on www.realgpx.com).
Make a backup of your game_snd.bnk in your \GP4\Samples\ folder and load it
Load each sample to their assignated slots (100-110.wav in slots 100 and 110
and so on).
Copy the engine.txt file in the \GP4\Samples\EngineData\Preset1_Cockpit\ and
\GP4\Samples\EngineData\Preset2_OnCar\ folders, which you, of course, made
backups of.