I have a PPE Hot +2 running on level 4 And lask tank I got 17.2 Mpg 570 miles 33 gallons to refuel. The problem is I've never seen anything higher than in the 16's even with the 265 tires driving all highway to California. This tank was mixed alot of in town driving and several 15-20 mile highway runs.

I have the PPE set on 34.25" tires which is the closest to my 34.36" tires

I also sometimes think the speedometer is reading high other times it seems okay.

Anybody else had a problem?

Anybody I just drove out of town and I am certain the sppedometer is way off

Nope...mine is pretty close, I believe it's about 1 1/2 mph high. I hardly get on the highways, or freeways, yet I'm getting pretty close to 17 mpg.
Btw, I have 285's and stock 3:73 gears.

get a GPS and see how close it is

get a GPS and see how close it is

I did what you suggested it was 3mph off which was alot closer than I thought it was. I had to adjust tire size to 32.75 to get it to read the same as the GPS which makes no sense