In article ,
(JimT96309) wrote:

I am currently interested in an older C-172 (Cont. 0-300 engine) that has an
STC for auto gas. My questions a

1. Can I continue to use AVgas instead of auto fuel?

Yes -- the STC allows mixing and switching back and forth.



2. I often fly into/out of Big Bear City, Ca. (elev. 6500ft.) I've been
able
to get out lightly loaded (me and one in the right seat) at a density
altitude
of 8,100 with one of our clubs 172s with the 320H2AD engines at 160 hp. What
difference would I see with the 15 fewer horses up front?


How do you get 15 fewer horses? You may actually get a few more with
mogas.


3. Can you give me a rough idea of cost to add a 2nd Nav-comm with
Glideslope
and then have the whole thing certified for IFR? I would probably try to find
a
good quality used one from one of the local shops.


I can't help you there. Check with some reputable avionics shops.