The .drg files are the tune calibration files themselves. Can't do anything with those files unless you have the Diablosport CMR software, which costs thousands of dollars. Log files end with .log and can be viewed with the Diablosport DataViewer software (download from this page).

Some of the feeling of "bogging down", then taking off like a rocket around 3000 rpm could be attributed to the boost curve of the turbo:




There aren't huge gains below 3000 rpm, but it also shouldn't be "bogging down" compared to stock. Don't expect it to drive like a big V8. You have to get the rpms up above 2500 and give it some throttle to spool up the turbo and create the power. If you try to drive it like a big V8, or expect instant snappy throttle response like a big V8, you'll be disappointed. Adjust your driving style to take advantage of the way the turbo works, and you'll have a lot of fun. Smooth throttle transitions give better results than stomping on the throttle, and don't be afraid of the upper rpm range.