Brsar Patcher Mkwii
I'm not sure if they auto loop on MKW, but I may not remember correctly. You may need to patch them with the BRSAR Patcher, if you aren't running these through CTGP. Not sure if this still works but you could try it out - Also Koopa Cape is a multi channel track, which may be the cause of the echos. You'll need to use a multi channel BRSTM there. MKW BRSTMs are slightly more complex than ones for Brawl / Project M, since sometimes you need to speed stuff up for lap 3 too. You might find that making your own custom music will be more efficient also.
File Extension Brsar
Universal BRSAR Patcher by soneek at 4:21 AM EDT on May 5, 2013 I'm not sure how many people this will be useful for, but eh. There might at least one person that.
You can learn how to make them / make multi channel ones here also: Hope this helps. I'm not sure if they auto loop on MKW, but I may not remember correctly. You may need to patch them with the BRSAR Patcher, if you aren't running these through CTGP.
Mkwii Brsar Patcher
Not sure if this still works but you could try it out - Also Koopa Cape is a multi channel track, which may be the cause of the echos. You'll need to use a multi channel BRSTM there. MKW BRSTMs are slightly more complex than ones for Brawl / Project M, since sometimes you need to speed stuff up for lap 3 too.
You might find that making your own custom music will be more efficient also. You can learn how to make them / make multi channel ones here also: Hope this helps.