Interesting. Does your's SS have the brake booster assist kit installed?
The early SS's with automatic trans. had issues with low vacuum to the brake booster. Chevy's fix was to install an electric assist pump for the SS owners with this problem. Not sure if it was a recall thing, TSB or what.
If you don't have this pump kit, you may in fact be having a low vacuum problem.
Hopefully someone with a little better info can answer in on this thread. I was only repeating some info I got off this forum. Mine is a 2010 w/5 spd so the assist pump thing doesn't pertain to mine.

 

I don't see anything extra between the booster and the manifold, just a hose. Sure feels like a low vacuum issue, had p/b cars in the past with low vacuum and it feels the same. Guess it's just something to live with. Found this thread - https://www.chevyhhr.net/forums/ss-specific-service-issues-repairs-61/2008-hhr-ss-brake-issue-buy-back-18413/ - and I'll give letting it warm up a bit longer and see what happens.

Thanks!

 

Don't think they were mounted on the topside. I seem to recall someones post saying the unit was located down low between the oil pan and the IC piping by the radiator. I don't believe it can be seen from the top side.
I want to say bigjack was the last member I recall talking about this, but I could be wrong.
Seems the later threads were about the assist pump and having the GM turbo upgrade and some of the reflash problems associated with it.
I hope someone else will answer in on this and set my facts straight. Just trying to help you out OKIE. Hope I'm not confusing you or giving out any bad info.

 

If I get a chance to get underneath I'll look for anything out of the ordinary. Not sure I'd recognize it if I saw it but who knows...

Thanks again for everyone's help.

 

OKIE. Try this thread. Scroll down to post #9. It has some pics of the assist pump. https://www.chevyhhr.net/forums/hhr-ss-45/how-do-i-know-if-i-have-brake-vacuum-pump-kit-intalled-44863/

 

Thank you! I'll jack the car up in the morning and take a look.

 

No such pump I could find. I did allow the vacuum to build to 18/19-in before backing up this morning and no problems arose. I also noticed vacuum was about 2-in on initial start and took about 30 seconds to jump to 10 then another few seconds to get to the 18/19 range.