So I have a new Diablo Predator, A Hot Edge Juice w/Attitude, no tranny upgrades, a straight piped stock exhaust, and thats about it for now. Would it be safe to max out both tuners just a few times, just to see what it feels like, as long as I let off before 4th gear? What about for a couple dyno pulls?

If not, what is the max I could go safely?

What setting/s would be best for mpg?

I plan on some gauges next, followed with an intake and an exhaust.

You'll get away with it for awhile but eventually if you drive hard it will catch up with you. I drive around daily and even pull a trailer with my bastard stack but I am carefull about how much fuel I give it. Unloaded I've done a few 1-3 blasts and even once into 4th to see if I could get slip on the edge and I had none. Just becarefull and use it wisley.

Before I forget I ran that stack for awhile and set the pred on 65 and edge on level one for all around use. Both maxed it ran good but changed to the bastard stack cause I got the quad cheap.

Don't do it....you'll never undo it...BTDT
Dyno's won't hurt the tranny.