[AgingYoungster_PA]

I am pretty sure you might get a CEL. When I took my VN off the jack stands I took it out and gently drove it around some back roads. Then I hit the highway and let her rip. I did an oil change before the lay-up and treated the gas of course. I recall one small stumble after I first started her up. I idled a bit longer than usual too o ensure good fluid flow.

 

[AgingYoungster_PA]

The louder exhaust would suggest the exhaust valves are open longer (high speed / power mode). Are there any codes in the ECU? There might be some warning codes. If you have those then the dealer might have something to work with. When the 2ZZ in my Vibe GT would hit 6400 rpm the high speed cam lobe would be engaged. Then it got really loud and would pull like a turbo...to 8200 rpm (beautiful sound).

 

[AgingYoungster_PA]

Mine was stored for just over 3 months and aside from a small stumble after startup everything sounded and ran fine. I have fuel stabilizer plus Marvel Mystery Oil in my tank with regular gas. I did an oil change before storage. That is it plus periodic battery charging. I have a quarter tank left after driving it around on the old gas. I want to take it down to about an eighth tank and fill it.