Can I simply replace the factory 2-ohm sub in my 2004 CL55 with a 2-ohm impedance shallow mount subwoofer without problems?

The stock sub (blown) is a 2-ohm speaker. I'd like to fit something aftermarket in the stock location.

You shouldn't have a problem, just try to match up the power rating of the new sub with the stock amp. Rather have the amp a little stronger than the sub than the sub too strong for the amp then turn your bass down. Otherwise, your new sub is going to sound like crap.

Also make sure the new sub is a free air

Helix makes a shallow sub that fits in the location of my stock sub. I'm not at home or i could tell you the impedance. I can't speak to pairing it with stock Bose amp as mine blew so I am putting in an Alpine amp to run the Alpine HU, Bose OEM speakers and Helix sub. Good luck.

Thank you. Doing more research but kind find any power rating info on factory BOSE amp. I posted a new thread seeking advice on how to best achieve my end goal of improving sound quality. The subwoofer alone wont solve my problems.

Understood. You would be surprised how much sound quality is improved by just adding in a modern head unit and sub does. I confess that I did a stutter step of first adding a powered sub with the after market head unit and it was really noticeable. When the factory amp died I decided to replace it with an after market amp and the helix shallow mount sub. The powered sub will most likely go on ebay. In terms of specs on the factory amp there are labels on the sides of it with serial and model numbers. I would just google those. One last thing, if you plan on using the wiring from the factory sub to the after market sub, be advised that the factory sub wiring is a pretty thin gauge of speaker wire, nothing like the monster cable used in current sub installs.