i have had Lew custom tuning in my G8 GT and GMC and its a very noticeable improvement even over the canned tunes. You wont be dissappointed.

 

Any vehicle dyno tuned custom street tuned should have an advantage over a large company's canned "safe" performance tune. The larger company has much more exposure to risk but have also done their homework well with in-house software engineers along with tuning specialists. Having said that I have the Diablosport inTune for my 2011 Silverado 1500 6.2 and happy with the results. I run 93 octane with a mail order "Lew Tune". The truck performed noticeably better and later I tweaked the tune a bit more which woke up the truck even more. For the convenience, packaging and increased performance that the Diablosport product can provide I feel it is a viable and legitimate option.

 

Looking into buying one of these glad there a some good result for a stock truck slightly modded...

 

With the handheld, if you learn how to tweak the timing, you can get a better result than the Cannes tunes. You have to read the plugs to get the best result. Don't always rely on the log 100%,