I've done my homework, ie (googled and searched this forum), but still have some specific questions.
1) My gears and tire size are different from stock. Those of you w/ the Predator and/or Flashpaq, how to you calibrate your speedometer? I'm aware of the higher end units w/ the gear ratio options, but they are out of my budget.

2) SC can alter shiftpoints and DS can't. I only drive my truck for towing/hauling, otherwise it stays parked. SC owners: Do you utilize this shifting feature while towing or just for racing applications (red light to red light fun ) Not sure if it would be hard on the tranny banging gears while towing?

 

Gear ratio has NO bearing on speedo as 3rd Gens are read off the ring, so ONLY tire diameter influences the speedo. Either tuner will adjust your speedo just fine.

I've run both on my '04 and for me there was NO comparison. The SC with it's tranny tuning was/is heads over the Diablo, but to be fair, Diablo does NOTHING on my year transmission. On a year with tranny support, it may be more apples to apples...

 

Dang, that makes sense the ring sensor (that looks like a giant sprocket w/ little teeth) turning each revolutions w/ the diff. Good one!

Now, do you tow with tranny modified, if so, which setting on the SC?

 

My WOT shift points are pretty aggressive, but who tows at WOT? LOL. Shift schedule outside of WOT is more aggressive than stock, but nothing radical except I have torque management reduced by 80%.

I stay with the performance tune 98% of the time, I actually find that the Perf Tune with 93 octane gas gives me the best MPG over any other combination, even enough to offset the fuel price.

I used to tourney bass fish very regularly, last boat being a 19' with 175 HP motor. Boat, motor, trailer & gear probably around 3000 lbs. NEVER changed from the performance tune despite that SC recommends doing so when towing/hauling over 2000 lbs.

Now I do tow a heavy tractor/dual axle trailer combo about four or five times a year, weight just under 8000 lbs. and I change to the tow tune for that. I just pulled my Grand Cherokee to a shop around 30 miles away not too long ago and did change to the tow tune for it as the weight is around 4200 lbs. and I had to pull a couple of steep causeways...

 

Thank you for your feed back, I value it very much!