Exhaust
08-12-2014, 09:29 PM
#1
New Member
Thread Starter
Join Date: 06-17-2014
Location: missouri
Posts: 12
Exhaust
Ive had my hhr for about 2 months now. It's an Lt 2.2. I was looking to do a cat back system. I think the stock piping is 1.75 inch. I was looking to go to 2 inch piping. I had 2 muffler shops tell me that I would see no increase in power with a cat back, and that I would lose back pressure and lose mpg, and possibly mess with the sensors..They would only recommend a cat back if I chip the computer and/or use a programmer. I have done exhaust systems on other cars, and have had no problems, but they have all been pre-2000 vehicles. Are the muffler shops telling me the truth?
08-12-2014, 11:10 PM
#2
Deceased
Join Date: 06-30-2010
Location: Kannapolis NC
Posts: 25,739
First off, 
to the forum!
Let's just say that they are shading the truth, or feeding you misinformation due to ignorance.
I'm running two GMPP/Borla cat back systems, and one Magnaflow cat back system, with no problems.
My fuel ecomony stayed the same, my "butt dyno" says I may have picked up a handful of horsepower, but not much.
And you definitely want to stay away from the so-called chips out there for HHR's, they are a waste of money. Now a Trfecta Tune is a good investment, as anyone here who has one will tell you. Do a quick search on "Trfecta Tune" at the top of the page, and you'll find lots of info.
If you don't decide to go with a tune, disconnecting the NEGATIVE battery cable for 30 minutes minimum will place your HHR into "Learn Down" mode. That will allow it to adjust for the new exhaust by changing fuel trims, etc.
to the forum!Let's just say that they are shading the truth, or feeding you misinformation due to ignorance.
I'm running two GMPP/Borla cat back systems, and one Magnaflow cat back system, with no problems.
My fuel ecomony stayed the same, my "butt dyno" says I may have picked up a handful of horsepower, but not much.
And you definitely want to stay away from the so-called chips out there for HHR's, they are a waste of money. Now a Trfecta Tune is a good investment, as anyone here who has one will tell you. Do a quick search on "Trfecta Tune" at the top of the page, and you'll find lots of info.
If you don't decide to go with a tune, disconnecting the NEGATIVE battery cable for 30 minutes minimum will place your HHR into "Learn Down" mode. That will allow it to adjust for the new exhaust by changing fuel trims, etc.
08-13-2014, 05:46 AM
#4
New Member
Thread Starter
Join Date: 06-17-2014
Location: missouri
Posts: 12
thanks for the welcome..i was looking at the magnaflow or the super 44's. Ive heard some cobalts with the 2.2's and they sound ricey with the mags. The super 44 had a deep tone but still restrictive compared to the wide open magnaflow.
08-13-2014, 10:17 AM
#5
Premium Member
Join Date: 08-09-2012
Location: Cambridge, Ontario , Canada
Posts: 1,979
i have a 2.2 with the magnaflow cat back..i like it, nice sound..only problem is SOMETIMES you get a drone at certain speeds, like on highways, but I just turn up the radio volume and its all good, but also it doesnt really bother me, i love the sound :)
08-13-2014, 10:21 AM
#6
Premium Member
Join Date: 08-09-2012
Location: Cambridge, Ontario , Canada
Posts: 1,979
i doubt you will gain any HP from just a cat back. I changed my air intake, exhaust manifold/header and swapped to a bigger/more free flowing downpipe from ZZP, plus the cat-back magnaflow. I also tuned my car via HPTuners and put it on a dyno. With the tune and the mods I only could gain about 5HP. thats the max I could get out of it