Fellas, 93 FLHS. I had a weird whistle exhaust noise at idle last summer. The bike had long drag type pipes with fish tails. I contributed the noise to the cracked rear pipe. This year i put on true duals and now have a stranger noise. At idle the front cylinder sounds great. Rear one has a wooshing type sound without the "pop". Starts and runs fine. Sounds ok off idle. Any thoughts? I did just re-ring the bike and rebuilt the heads.
Cheers

 

Check for an exhaust leak at the head on the rear?

 

I've checked the exhaust gaskets. Its a weird sound. Maybe its normal.