Temperatures look pretty good to me. I assume that the mobile Barton puts out as much heat as the TBredB I test with once you give it 1.85V, so those temps seem completely reasonable. I wouldn't bother upgrading the L20 personally unless you decide to watercool GPU/nb as well. The L20 doesn't have a large amount of head, but it's quiet and small. Your Maze4 isn't the best waterblock around but it is low resistance. You may well run into a situation where you upgade CPU block and then have to upgrade pump and then need more rad ad infineum.
I would suggest that you post a picture of your cooling loop. We can then find any plumbing issues that might keep you from getting the most out of your system. Then I'd suggest trying out reversing the fan on your radiator to get fresh outside air into the rad. If that makes a big difference then maybe you could fashion some kind of duct from the front 5.25" bays to the heatercore so it gets outside air?
BTW welcome to the Pro/Forums
