The FJR is back in the garage. Apparently, it’s fine. The noise I’m hearing is the air injection into the exhaust system to ignite any remaining unburned fuel. The 2007 and 2008 FJR on their showroom makes the same noise on deceleration.
Part of the problem is that the bike is still stock, so is running lean. To really get that smooth roar, I’d need to do a complete Stage I exhaust and add a Power Commander III.
Maybe I just expected the engine to be a little smoother, soundwise, than it actually is.