I have the K&N FIPK on my 07 2.4 and after the installation, I dyno'ed the truck. I've also installed and tested the Airaid but it didn't fit a five-speed truck properly so I took it off. For more details see:
https://www.chevyhhr.net/forums/show...t=22872&page=2
Scroll to the bottom of the page for the installation and testing article.

 

For performance, you can't beat the stock setup. They really did a good job. I changed out the filter with a K&N because you only have to buy once. Even with the recharge kit, you only buy once.

But if you have to buy one, get the GMPP.

 

^ x 2 ^

 

Anyone ever fab a intake up out of manderal bends? I was curious only because ive done this on many of my cars for cheap. I was thinking about doing it to the hhr and piping all the way down in the fender well area to keep the filter out of the engine bay for more of a "cold air" type set up. would you throw codes doing this? Not to sure how tempramental(sp?) these hhrs are....dont mean to jack your thread but if your a fabricator its something to consider..

 

The factory air box actually works pretty well. I added a K+N replacement type filter but I moved the factory cold air intake to the other side of the housing and now feed it cold air from above the radiator. It did require cutting the trim off the stock box too.



Cold air intake for about $25

 

I still think the best thing for mine was to punch a hole in the hood and mount a Hilborn style air scoop on there. Not only looks "old skool cool", but breaths really well with the dual exhausts and side pipes. Ironically I get better mileage in a pouring rain than normal weather driving. Check out my bio pics.

 

IF you install this one remember to re-set the ECU.

 

How do you reset the ECU and why do you need to reset ? Thx

 

I've never bought a k&n filter alone so I can't say much about going that way other than I know a lot of ls1 people that I know do not like them. I currently have a CGS and am very happy with it. I can feel a difference with it, I know seat of pants doesn't always mean much, and have not had any problems with it.

The easiest way is to just unplug the battery for about 15 minutes. It's not necessary to unplug it, but once you install an intake you can and it might help the ecu learn that their has been a change made quicker.

 

Ive got the GMPP intake plus the GMPP performance exhaust on my 08 2.2L and I'm quite impressed by the performance. The only draw back is the air box sits on top the engine and really heats up, go long and far enough and you can fry an egg on the shiny top cover, so much for cold air, fresh maybe, cold not so much. I'm toying with covering the outside of the box with dynamat to help deflect some the engine heat, can't hurt right.