I live in Silver city, NM,elevation 6,000 ft.  Most of my riding is between 6-8000 ft.  I have two savages.  One has stock jetting and the brass plug over air mixture screw untouched.  The needle  has had the shim mod.  And it runs great.  My other savage has the shim mod, larger pilot jet, brass plug removed and it  also runs great.  My advice at this altitude it to shim the needle and call it a day.  RE different exhaust.  I have tried several.  None of them required carb changes.  My first pick for muffler mod is eight 5/16" holes.  Second pick is the dyna muffler.  I have tried others as well, but they are  not worth mentioning.

50 pilot and 150 main would probably be good for you

55 pilot is too big, 150 main should be fine

  He's running 50/ 145  jets, neither of these should cause the sparkplug to be covered in soot. If anything the bike should be running normal or a bit lean.  he should be looking to see if the spacer mod was done by the PO ,seeing the bike was set up for 1000 ft/sea level and was running a 55 pilot earlier . logic tells me it's getting extra fuel at mid range rpm ,either the needle jet is set to high (may have only 2-#4 washers), or the float bowl level is to high for what ever reason.

Thanks for all the feedback everyone! So to answer a couple things. Verslagen mentioned petcock. I changed it to a raptor before coming to New Mexico elevation (I think the diaphragm was leaky when I bought the bike).

Here at 7000+ ft I've tested the stock pilot (52.5) and one step lower (50) and I feel the idle and performance is significantly better with the 50. Screw is currently at 2.5 turns out with the 50.

If I feel like taking the carb off and getting into some cleaning in the near future, I'll check the spacer to see if it was modified. PO said he changed the jets from stock, but didn't mention the spacer, so not really sure about that. He may have had a shop do the change and perhaps they modified the spacer and he didn't realize.

And if I get that far in I'll check the float as batman said.

Drove about 100 miles today between 7500ft and 5000ft, mostly 55-60 on the highway but with some city driving as well. Got about 55mpg. Before, with the 150/55 jets at 1000ft was getting around 43mpg.

Another thing, non jet related...

Have had a much harder time guaging my oil level in New Mexico. Running Rotella T4, the same as I was in Kansas at 1000ft. In Kansas, the level stayed pretty constant regardless of the engine temp. But here I'm finding that with a cold engine I'm somewhere in the middle of the sight glass. After a good hot run I'm above the top line, sight glass completely full or very close to full.

Wondering if the Rotella 15w40 is maybe not the right choice for Santa Fe, even in summer. Temps fluctuate between 60 and 90 at times.

And in the morning the oil will go back half circle?

Let your engine cool before checking it