I did not have much to do today so I went out and changed the clintanary valves on the wifes HHR. I think the preformance went up by 10 to 15 percent. Just wondering if any one else has done this. Not hard to do. While doing this I also put in new muffler bearings and rotated the air in the tires. Not any improvement in performance but it does look better.

 

You should have changed the blinker fluid too.

 

A little K9P will also give you a good kick in the pants!!!!

 

You can also change the halogen fluid on your headlights it makes the light look a lot whiter than stock fluid.

 

I tried this and could not get all the air back in. How did you keep the air from getting away?

 

Try reversing the polarity, my first car ran better with a positive ground. (1955 Studebaker Champion)

 

Might have to check with the ID10T programmers to get the performance of the DIC upgraded.

 

Its not legal alter the DIC in Utah. We have some strange laws here. You even have to have a reclaim system when you change the air in your tires.

 

But I figure I can get at least 2-3 MPG with the right adjustment.

 

I've personally done this, and have seen a 12.7% increase in blinker speed and luminosity, both which have contributed to smoother turns.
Other similar mods include:
- I've decreased the granularity in the windshield for increased clarity
- I've switched the air between the front and rear tires; I did this because OEM specs call for the denser air in the back, but I disagree with this placement, as the (heavier) engine is in the front
- I've filled the pores of all zenith-facing leather with color-matched filler to help mitigate crumb build-up
Other performance-improving mods to come.