I agree with Roger. My trips are usually 300+ miles, and I generally fly them in the 9500 - 13000 ft range. My 337 is N/A. No T, no P, not even O2 built in. Instead, I have the "tank+snorkel" from PreciseFlight, with a conserver that makes it lasts over 600 miles for 2 people on board. I fly the Rockies as well, and the N/A has never had a problem.

Bottom line to me as well: Keep it simple.

ipasgas - note my post today re. landing the 337. That was at LUK with an instructor named Ralph who unfortunately passed away . We flew a complete pattern to touch down "hands off".