Definitely spend the $ on quality parts and do as much as you can youself (or at least as much as you feel like doing) to save the dealer prices. My laundry list from the initial dealer check up resulted in about 1200.00 of parts and labor. They got about $500.00 and two hours of my time wasted. I watched them park it out back for an hour before starting work on it even though I showed up at my appointed time and let me sit there about 35 before complaining got them to bring it out about a half hour later. The bottom line is they got to pull the intake and replace and warranty the knock sensors. I ordered the GM o2 sensors and replaced them in my driveway in about 20 minutes. Saving about $600.00