I ran into an older guy one day riding a 77k whom I noticed was running so after reading a lot of threads about this subject I just had to ask him what mods he had to do to run them and he said nothing!His bike was stock with a cheap 4 into 1 and it ran and sounded very well.As a side note he never heard you could not run them witout mods he just hated the stock box.just my two cents.