Yeah, I love my gryphon tune.

 

Put some more miles on today and I'm still satisfied. I can tell there is more midrange power as I get up to highway speeds quicker. Still haven't really romped on it. Shifting is perfect and crisp. I'll pull my trailer 250 miles tomorrow so that'll be the real test. I'll let you know.

 

Made my trip today. My trailer is a 12 ft single axle with a 4 ft gate. The cargo is my 2000 lb Mule Pro FXT and some deer corn. The truck pulled better than stock but still leaves me wondering if something isn't right. It has a hard time maintaining 70 mph up moderate hills with OD off running about 2800 rpms. I'm really worried that when I face any type of headwind I won't be able to even maintain 70 on flat ground. The mule sits high and has a top and windshield so it's like dragging a sail. Today I got 8 mpg for the trip running 68-70 mph. My 2015 Eco pulls it at 2200 rpms up any hill and I get 11 mpg. My previous 6.7 PSD pulled any hill in OD and got 13 mpg. The 5.4 gets up to 55 mph nicely but above that it really struggles. Maybe this is normal I just haven't had a NA truck since I can remember.

 

Doesnt sound normal to me. I pull my 28' pontoon with ease. You have seen how high up on a trailer those sit. I would email 5 star and see if they will set you up to data-log and get a true custom tune. Even though they say "custom tune", it's NEVER custom until they read your data logging file and tune to that. They base their custom tune off what you tell them you have as far as supporting mods (intake, headers, exhaust type, etc). Until they read your data, its still a generic tune in my book.

 

I pull a 20ft flat bed with 5 full size atvs with no issues at all. Maintain 75 with ease and got about 12mpg. That was with no tune at all either. I towed a 16ft flat bed with an amc eagle on it about 100 miles and it did great with the tune. I averaged about 13mpg. And was doing about 65 because of the trailer tires.

 

Well that's not encouraging. The truck seems to run perfect. Doesn't seem underpowered without a load. I can't imagine what would cause a loss of midrange power but wouldn't cause other issues. I get 12-15 MPGs unloaded and from what I can tell that sounds about right. I have stock size tires but they are the heavy 10 ply M/Ts. I think the truck also has a leveling kit. Would removing the level help much??? Other than a Magnaflow muffler everything else is stock. I have 3.73s which put me at 2700-2800 rpm at 70. I'm wondering if 4.10s would help me much. Not sure I'm willing to spend that money anyway. This truck is just my weekend hunting rig and as long as it doesn't break down I'll probably just let it be. All maintenance is up to date.

 

I have 3.73 as well. Lift has nothing to do with fuel milage or power. Tire size does. I am towing on flat land. I'm in Florida so the biggest hill we have is a bridge.

 

I didn't catch what kind of weight you are towing. I have the 5.4 and pull a toy hauler that runs pretty heavy, about 7500 pounds loaded. I'm fine on flat, but steep hills are a struggle. I don't want to tax the tranny too much, so I'm content with getting in the slow lane and going 40. If I put my foot into it, it will downshift and go faster, but I see dollar signs doing that. Before I regeared to 4.56, when going up a hill like that, it would not downshift when it felt like it should and keeping even 40 was tough, and would be in the 3900 rpm range. After the re-gear and a Towing tune from MPT, it shifts firmer and sooner and keeps the rpms in a good spot. I would not expect to be going 65 uphill with any serious load on this truck.

Oh yah, i have 35's, which was why I re-geared.

 

I'm only pulling 4,000 lbs at most but wind drag is the main factor with my load. I used to have a 30 ft bumper pull travel trailer and this load pulls almost as hard based on pulling both with my old 6.7. I should also mention that I live at 4000 ft elevation in the western Texas Panhandle. I wish I could get 4.30 gears for a 4x4. I think those would be perfect.

 

4.30's in 8.8 reverse has been impossible thus far. I am currently rocking 3.55's in an open and want to go to 4.30, however cannot find 4.30 for front. It looks like 4.56 is it, but that seems like a lot of gear for a 33" tire. I guess on the upside it should move out nicely?