I bought my '06 Street Glide used. I had no reason to suspect the mufflers were not correct, since they were obviously OEM Harley mufflers. Then I noticed in a factory picture of an '06 that they came with slash-down mufflers -- mine are slash-up. So after looking up the part numbers stamped on the mufflers (65547-07; 65354-07; for HARFLT1584) I realize these are not original. They came off of an '07 or '08 Road King. This explains the style (slash) difference, and the fact they're they're for a 1584 CC (96 cubic inch) motor. Also, there is a cat in the right muffler.

Question #1 -- would mufflers designed for 96 inch motor flow better than mufflers designed for an 88 inch motor, and would there be an appreciable performance advantage if the 96 inch mufflers were installed on an 88 inch motor? Or were they installed for some reason other than performance? (okay, that was three questions in one).

Question #2 -- what would flow/perform better on an 88 inch motor, these OEM 96 cubic inch mufflers or Jackpot Dyno Tuned mufflers WITH the Quiet Baffle AND Quiet Insert BOTH installed? (It does have a Stage 1 AC and PCV). I ask because on long trips I find the Jackpots too loud without the Quiet Baffle and Quiet Insert installed. So now that I know my "stock" mufflers were really for a bigger motor, I'm wondering if I gained much.

 

Unless those mufflers were California ones, there should be no cat in the right one. In 07 the mufflers were changed, they are a bit louder at idle but quiet down at higher rpm's. Or vice versa, I can't remember now and mine have been off for a long time. They were supposed to flow better than previous models.

 

Thanks, Guntoter. Anyone else?

 

it is a very common upgrade as the new mufflers flow better.

 

You'd be happier putting SE's on if you're leaving motor mods to basic air cleaner and efi remap upgrade.