Droopy,
I am assuming you are referring to the 11th and 12th strings. Based upon this assumption, I imagine you are probably playing mostly E9th stuff.
Let me give you a little history of what happened; and then you can decide on what you want to do.
When the PSG began (as we use it today), Bud Isaacs put a pedal on his multi neck steel that basically brought two of the "standard" lap steel tunings into one tuning. I will explain.
Prior to Bud doing what he did, the 3 most popular tunings for the lap steel were:
A6th
E7th
C6th
Many of these were 8 string necks.
So was Bud's guitar that is; his lone pedal changed one of his necks from a basic A tuning to a Basic E tuning. Back in those days few had a high G# and cetainly not strings 1 and 2 like on the Standard E9th tuning of today. These all evolved later.
Since "Bud's" pedal (later split into A and B), brought two of the three "popular tunings" together, Most PSG's were built with 2 necks and had 8 strings each. The top neck was of course a neck that gave us "that sound", and pulled the E7th tuning into an A tuning with a bottom that was a rarely used "suspended tuning".
The bottom neck was used like the prior lap tuning of C6. Since I assume you were not around when this happened, C6 may be totally foreign to you. But C6th was very popluar tuning that was invented by Jerry Byrd.
Buddy Emmons and others added pedals (and later knee levers) to the C neck. They of course had used lots and lots of "slants" (on their lap steels) to get what they now get with pedals and knee levers on the C6 neck.
From the getgo, some (I am one) felt that 2 necks was not necessary. I will even go one step further and state that IF, the PSG had been first, there would only be one neck today. Such was not the case and there is no way to ever prove this. But those of us who lean towards a single neck found quickly that there was great similarities between the two necks; which may NOT seem so to those who didn't evolve with it.
Thus, the universal was born. But there was one big caveat. In order to simulate the chords that could be gotten on the C neck (double neck PSG's), it was mandatory that two more strings be added on the bottom. Such was the 12 string Universal which you play.
Since I assume you are not playing much in the B6th (C6th effectively) mode, these two bottom strings can be a bit cumbersome playing mostly E9th stuff.
So I agree with the poster that suggested taking these two bottom strings off. If you do this, you will have a psuedo E9th tuning, albeit the 9th and 10th strings will be B and G# instead of D and B respectively. You probably have a knee lever that raises your 9th string from a B to a D. I would strongly suggest you raise the 10th string from a G# to a B also with this knee lever. Then you will ALMOST (not quite) emulate exactly what is done on the E9th neck of a D-10 (or S-10).
As to "Extended E9th", now that would open a lot of possiblities for you. It would be EXACTLY like the standard E9th tuning WITH two more notes on the bottom. Which can really embelish your playing if you take the time to explore and use them.
Your tuning (Extended E9th) would look like this (open strings):
F#
D#
G#
E
B
G#
F#
E
D
B
G#
E
You might have to rearrange some pedal and knee lever pulls possibly. But since I assume you play mostly E9th stuff, it would be a great E9th tuning. Remember if you do this, you messup the B6th(C6th) bottom. Die hard U-12r's (like myself) shutter at that thought
. But that is because we are so used to our C6th grips. NO way could I personally ever go to Extended E9th. But hey, a lot do it and love it.
So think about it and go for it
And may Our precious Lord and Savior bless you in your quests,
carl