With the custom tune, you'll gain even better/quicker throttle response & acceleration, stronger/harder pull, smoother & quicker power delivery throughout the rpms, etc...
as far as gains go... absolute hp/tq gains are hard to predict... every vehicle is different... even if they're the same and have similar mods... location/weather, fuel used, elevation/altitude, etc etc all play a role... the same holds true for mileage gains - those variables, plus driving habits/style, how much highway vs city driving, etc all make a difference.... you could gain no mpg increase, or you could gain up to about 2 mpg increase...
tough to say due to all of the variables in play - which is why there is no guarantee of any specific/certain amount of hp/tq or mileage gains.
with the custom tune, I CAN tell you that you will definitely have a very noticeable performance difference/gain over and above the canned preset diablo tunes...
I have gained people anywhere from 12-39hp, and 10-23lb. ft. torque...and 0 to 2 mpg... again, obviously mods, fuel used, driving style/habits, etc all played a role in who gained what...
my complete custom tuning is only
$135 USD...
Here's info about my custom tuning:
http://www.diablewtune.com/
there are links on there to the info you'll need - i.e. how to import/export the tune files I need from you, how to do a data log, what parameters to log, paypal "Order Now" button for purchasing the custom tuning, etc... as well as a link to just a small sample of just some of the "Testimonials" I've received from people I've done my tunes for - makes for good reading, hehe.
What I'd need from you is a copy of your "original backup" stock tune file, a copy of the "last tune written" tune file, a steady driving datalog, the paypal, and that's it... then we're good to go. and I can usually have the initial custom tune done and sent back to you within 24 - 48 hours from the time that I receive everything.
You can find the info/instructions for logging and getting me the files, on my site
http://www.diablewtune.com at #5 for the inTune -- or at #4 for the Trinity.
==========
you can email me directly at diablo DOT help AT gmail DOT com
Thanks for asking man, I appreciate it!
-Lew