There are tons of posts about tuning.
I'd suggest reading up on it as it's not as easy as people make it out to be (unless they have countless hours of experience and know exactly what to do). I'd ask the guy a lot of questions about the HPTuners before purchasing too, but here is the way I see it. Even IF you don't know how to tune, it is much easier to have HP Tuners and have someone help you tune via e-mail and also teach you how to tune as well, so you can do the tunes and adjustments yourself as needed.
When I got HP Tuners, I'd never tuned a cobalt before, or any GM that is, but since then I've tuned a TON of guys, and now I tune all sorts of cars, but the DSM/Evo is still my strongest suit.
It's time consuming to learn how to tune as a lot of stuff will be trial and error for the LONGEST. But once you get past all that, then you're golden and won't have issues, but again, read a ton before using it, and I can't stress this enough. You have a couple values off in the tune and don't know what to look for while logging, you will blow up your stuff in a heartbeat.
---------- Post added at 12:27 PM ---------- Previous post was at 12:26 PM ----------
Shoot, even when you know what you're doing you can still blow something up lol. I went through 4 DSM engines on the DSM I owned before my evo, but that was because I was literally pushing it as hard as I could past the breaking point or "safe" zone lol.