I am looking for a daily driver truck as I wrote off my car last month

but i have a bit of a delima. I really want an LSx motor for the easy self tuning I can do with LS1edit (or at least I've been told i can self tune with that), but I dont want to pay for the fuel when im just driving around town. I was looking closer at an Envoy or Trailblazer with the inline6. My question is...can I tune these engines as easily? Has anybody modded one of these inline6 motors? Any input would help alot, common weak links, anyone with experience, you know.