Wilsons Sandbox

Hi gang: i have an A19 wiht over 300 miles on it, i installed the "quiet" serries supertrapp, no carb mods so far. initially had 10 disks on it but it was running hot, went down to 9 and it runs fine but does backfire when decelerating, as most 4 strokes do (with no antibackfire emmission controls). After 600 mile dealer "checkup" i do plan to remove the carb iddle mix plug and adjust that a bit. If mileage does not suffer, I will not do carb rejetting. JC