First of all I was happy to see that tune name here. Speed Highway is one of my favorite tunes from Sonic games 9well, they got lots of good music in their game- that makes them a winner!)
So it is cool to hear remix of that music.
The part that I was concerbed about1#-
the backdround music (i think it is brass) sounds louder than it should be..
#2- the music sounds a bit digital. try using some instruments that makes it sound less digital and clustered, but more continuous!
(I also played that audio on my piano using combination of string and piano.)