Yeah, I’ve been looking around the internet since this thread and there are a lot of fans of that atlas/vortec 4200 straight six. 270-290 hp and tons of low rpm torque depending on the year. I have an envoy too, so far all I’ve had to do besides simple maintenance is replace the coil pack, knock on wood.
Freegards
There are some nice tweaks you can do to the computer like turn off throttle management for example that’ll really boost the acceleration. I added a cold air induction kit to mine which gave me 5-10 extra ponies and improved gas mileage too. There are some nice tuning tweaks out there and last I looked a few years ago a few places that will custom tune a chip for you that’ll boost mpg and performance.