HT too loud or annoying neighbors?

[JJJMan]

Ok here is my situation. I've been living in a ground floor apartment for a little over a year now, had the same upstairs neighbors the entire time. Never had any issues with annoying neighbors or any issues with me. Lately however, I have been doing upgrades and more fine tuning of my HT system and apparently I have awoken the beast.

I will be watching an action movie (Ironman, Transformers as examples) that has a full sound spectrum, at between 8 and 10PM and during the movie I get BOOM BOOM BOOM on the wall from my upstairs neighbors. Even a "friendly note" has been put in the common area by the mailboxes saying how the bass is loud and annoying and it needs to stop because people have to be up early for work blah blah.

After carefully calibrating my HT to actually sound nice and clear, its apparently annoying my neighbors. Keep in mind, my sub (Sony SA-WPFT1 from a HTiB) is set at about 15% gain, and my Receiver is set to a volume of between 18 and 22 when the neighbors have made a stink.

So... am I doing something wrong here? Should I turn down my HT even more, compromise everything I have worked for? Or do they need to know they are being stubborn about this and I am not being any louder then they are on their hardwood floors (which sound like they are walking around in ski-boots 24/7 btw) Move the sub further away from my wall, get a riser for it? Any advice would be greatly appreciated.

TIA