I have decided to update this game with an amazing fix. The last fix I did I found it worked but it didn't last to long. This one here I so far have seen works to its full potential.
So lets get started!
Now the last time I said you have to install it directly to the root of the C: drive. Well we are going to do that but we have to make sure there is no subdirectory. So you'll want to install into the follow drive/folder which is "C:\Sega GT". That is it for that and the game should run and may have sound but you may also want to get this game running at a better resolution and perhaps that is 1920x1080p or if you have a 4k tv then a higher resolution.
So next up were going to want to install dgvoodoo2 to the Sega GT root directory. You can download dgvoodoo2 from https://goo.gl/Tg392C. Download the latest version which I believe is 2.55.4 older and newer versions will probably work as well.
So next up were going to setup dgvoodoo2 with Sega GT it should automatically be set to the Sega GT directory but if not follow the direction from the screenshot below.
Alright next up change all the settings as seen in this screenshot below.
First the General Tab
Next up were going straight to the DirectX tab ignore the Glide one cause were not using 3Dfx with the game.
That should be it for that. Now next up we want to make sure the game runs to its full compatibility. So we need to right click on SegaGT.exe and go to properties. From there we click the compatibility tab and run this program in compatibility mode for Windows 98 / Windows Me.
Alright the next step is definitely up to you I believe the game runs at 30fps and there is no way to change that without doing anything trickery. Of course I have the trick available for you right here.
Before doing this make sure you make a back up of the original SegaGT.exe file if you don't know what you're doing you may damage the game.
The following information comes from PCGamingWiki where you can find fixes for many games. https://pcgamingwiki.com/wiki/Sega_GT
(This may not work for you so go to my hex edit below the screenshot and it may help you better)
Here is my hex edit for the SegaGT.exe file cause the one above didn't work for me and looked slightly different. So if yours looks like mine then it should work for you.
Open your Hex editor and change the following:
Look for the following offsets
A5F00 change 01 to 00
89220 change 4D01 to A600
89250 change 4D01 to A600
897B0 change 4D01 to A600
Look for hexadecimal change 0000F041 to 00007042. Keep searching for 0000F041 and change them all to 00007042 until there is nothing left. Save and exit.
That is all the game should now run with Sound and all the Videos which are just two intro videos. With this hack there is only one issue and its kind of minor. The menu's will look rather ugly however you'll be in there doing some setup and that and its completely functional. The game however looks really good in 1920x1080p it will probably look even better on a 4k tv if of course you're a fan of them.
Now how about some screenshots: