These tracks are taken for the Evolution version of the game's OST, unlike the Super Arrange Version which are a remaster of the original tracks and are much older.
Credits to USS Enterprise for these.
Rename the files with "ALT" in the filename if you wish to use them over the other.

To install simply locate your installation folder and replace the files in the "BGM" folder.
You do not need to replace all of them, pick the ones you like.
Remember to backup the original files just in case.
While not required, in your installation folder you can also create another folder called "BGM1" and put another combination of files in there and in the settings menu in-game you can pick which folder it should use.
You'll see that the "Background Music" setting will have changed from "On/off" to "Original/[header]".


Below follows the original readme file from the author, note that installation instruction are innacurate but I kept them anyway.


The Legend of Heroes: Trails in the Sky First Chapter SAV Alternate Music Mod 
By Triplicity 

DISCLAIMER: I am not responsible for any technical issues or crashes you probably will not experience by using these files. 

These files replace a bunch of Trails in the Sky FC music with their Super Arrange album versions, set up to loop in-game.  The Zanmai (Luxury) versions of Sophisticated Fight, Silver Will, and Hollow Light of the Sealed Land are also provided and can be swapped in if so desired, though the last of those does not have a SA version and is used by default. 

Installation: 
0. (Optional) Backup the following folder. 
1. Unzip files to [...]\Steam\steamapps\common\Trails in the Sky FC\BGM, overwriting all conflicts. Use the tracklist below if you only want to use certain tracks. 
2. If you want to use the Zanmai version of Sophisticated Fight, rename Zanmai-ED6400.ogg to ED6400.ogg and overwrite. 
3. If you want to use the Zanmai version of Silver Will, rename Zanmai-ED6403.ogg to ED6403.ogg and overwrite. 

Uninstallation: 
0. Restore the backups you made during installation. 
OR 
1. Right-click on Trails in the Sky FC in Steam Library->Properties->Local Files->Verify integrity of game cache. 

Tracklist/Comments: tl;dr the sweeping orchestral pieces were the worst 

ED6001: I Feel Like I Could Dance with the Wind 
I Feel Like I Shouldn't Have Looped a track that no one will hear because it's The Title Screen Theme 

ED6102: Seaport City of Ruan 
Had to make up a loop point for this one. It's not the smoothest, but I'm reasonably pleased with it. 

ED6200: How to Walk in Liberl 
Unloopable as far as I know. This is the track that made me ragequit the project and forget about it for a while. Sorry. If you can find a way to make it work without cutting out a significant part of the song, by all means go for it and I'll even replace it in the pack and give you credit. 

ED6202: Rock on the Road 
This was the easiest track to loop in the entire set. Thank goodness.

ED6305.ogg: Hollow Light of the Sealed Land 
Despite being orchestral I lucked out with there being a fairly defined transition between the middle and ending parts. 

ED6400.ogg: Sophisticated Battle (Super Arrange) 
dat sax 

Zanmai-ED6400.ogg: Sophisticated Battle (Zanmai) 
dat guitar 

ED6403.ogg: Silver Will (Super Arrange) 
dem strings 

Zanmai-ED6403.ogg: Silver Will (Zanmai) 
dat piano 

ED6406.ogg: Those Who Protected Their Greatest Treasure (Zanmai) 
I think I had to make up loop points for this, but I'm very pleased with how it turned out, just like Rock on the Road. 

ED6502: Amber Love - Piano Ver. 
Original song: 0m54s Super Arrange: 5m50s. And no loop data to be found in either! 

ED6530: Princess' Troubles 
Pain in the ass (no good loop points) 

ED6531: Knights' Grief 
Pain in the ass (no good loop points) 

ED6532: Each One's Expectations 
Pain in the ass (no good loop points AND I had to do a lame fade out to even pretend it was a good cut) 

ED6533: Castle 
Actually not that much of a pain in the ass; the song loops by itself just fine 

ED6534: Colisseum 
Pain in the ass (bad loop points) 

ED6535: Duel 
Pain in the ass (no good loop end) 

ED6536: Princess' Death 
Surprisingly not a pain in the ass; the violins were kind enough to take a break and give me good loop points. 

ED6537: Finale 
Well, there wasn't a good place to loop back from, but luckily there was a decent place to loop back to? Pfft, who am I kidding; no good loop end, pain in the ass. 

Thanks for reading! Enjoy the music! 
All music by and copyright the fantastic Falcom Sound Team jdk