Size muffler
Senior Member
Joined: 08-29-2008
Posts: 936
From: NorCal BayArea
ok in the area of exhaust, what is the importance of the down pipe? And will the ecotec run right if you replace your cats with "test pipe" so long as the sensors are all put back in place? Lastly has anyone had there exhaust manifold P/P'd and is the difference truly as satisfying as a header? So after these changes are made, who actually produces's a tuner for our 2.2 HHR's?
! If you want to remove anything for increased flow try replacing the Resonator with a straight through pipe 
! 2) We installed a GMPP Manifold which is factory honed and we did some gasket matching 
! Most Manifolds are Out-Performed by most Headers but here in California they frown on "ANY" exhaust mods so for visual reasons only we chose the GMPP Manifold and just worked a little more on it's inside details 
! 3) Trifecta offers a tune for the 2.2 Engine !The one exhaust mod we did that really seem to help was to Ceramic Coat the Manifold, Down Pipe and the Straight Through Pipe back to the rear axle
! Although I have no numbers to verify this we have run the engine for "LONG" periods of time and when checking, the under hood temps seem considerably reduced, "Gotta Help that CGS Breathe" 
..... https://www.chevyhhr.net/forums/2-2l-performance-tech-5/how-build-your-own-header-save-%24300-bucks-15656/
Nice Job
! Really would benefit from a Coating :twothumbs!I will end this post that all of the above is from personal experience so I have "NO" documented proof, but I did stay at a Holiday Inn last night
!
Senior Member
Joined: 05-06-2008
Posts: 1,076
From: Over here
Senior Member
Joined: 01-29-2009
Posts: 205
From: Central, Ohio
okay, but I never said I was on-road, somebody assumed(not that there wrong but you know what happens when you assume), but if it prevents codes, then I will take that into consideration. So on the next step, what is gonna be the best bet for a header, and if I still haven't gotten an answer as for the purpose of the down-pipe, so far as I can tell it serves no direct purpose except for a convenient location for a cat and seing as how I want to run a header and bigger pipe I am under the impression that I can have all new pipe bent in the diameter I want and put a high-flow cat in. And no I didn't miss that the stock D/P flows well, but does that mean that a header is still an inch and five eights or whatever size that pipe is?
Senior Member
Joined: 08-29-2008
Posts: 936
From: NorCal BayArea
Well I Thought I Would Try and Give You Some Usefull Ideas for a Streetable Application ! What's the Purpose of a Down Pipe 
? To Connect the Manifold to the Rest of the Exhaust System !
Good Luck,
! What's the Purpose of a Down Pipe ? To Connect the Manifold to the Rest of the Exhaust System !Good Luck
,
Senior Member
Joined: 05-06-2008
Posts: 1,076
From: Over here
Senior Member
Joined: 01-29-2009
Posts: 205
From: Central, Ohio
I didn't say I wasn't, I just want the answers to my questions not you're opinions on why I shouldn't, if the idea will lead to an operation failure then throw a red flag, I do understand the laws, and thank you DLVRNIT, I am grateful for the help, I ask these questions because I'm used to carbed V8's not this emissions controlled stuff, and seeing as how I intend to change the entire thing I want to have a clean process. I only want to do this once
Senior Member
Joined: 03-08-2008
Posts: 505
From: United States of Texas
Flowmasters, Turbo mufflers and other junk.
I can tell you the Flowmasters and Turbo mufflers hurt the horsepower and flow.
Now the Cherry Bomb 88101 do not and they are very free flowing. I put one on my HHR and it sounds very good and you can see through it. It is not a straight through muffler as it has a diverter island in the middle but it is large and open inside with little or no restriction. It is obvious it has less back pressure than a Turbo or Flowmaster both of which I had very poor results on my race car with. Have not tried the Cherry Bombs on my race car but I am sure they would be very good.
Now the Cherry Bomb 88101 do not and they are very free flowing. I put one on my HHR and it sounds very good and you can see through it. It is not a straight through muffler as it has a diverter island in the middle but it is large and open inside with little or no restriction. It is obvious it has less back pressure than a Turbo or Flowmaster both of which I had very poor results on my race car with. Have not tried the Cherry Bombs on my race car but I am sure they would be very good.
Joined: 12-03-2009
Posts: 2
From: Hartington, Ont.
I have a 2006 lt 2.2, I cut the oem monster off and had a thrush glasspack put on that lasted for a month, way tooooo ricey. I then got brave and had a cherry bomb extreme put on, it is deep and throaty. I love it especially outside the car on the inside it is still a bit pitchy but outside it sounds like at least a V-6. Good luck if anyone cares it was the center center design for off road.