i had exhaust mods done back this winter which eliminated the resonator (i think) with a straight 2.5 inch pipe from the cat to the existing muffler where the resonator once was... they also put in a muffler similar to a flowmaster (cant remember the name) and it was all welded.. I went to the place with intentions of a 3 inch system and they said "i doubt a 3 inch exhaust system will fit under this car it looks too tight) so that is why i went with the parts i did...$130 didnt seem bad at the time

NOW.. it sounds good on cold start warm ups and doesnt drown or sound obnoxious like a pinging fart can on freeway (which they said would of happen with the flowmaster ones).... but when i do stomp on the throttle from a low end speed i hear a loud vibration sound. it might even be more noticeable if im in a turning motion..... do you think they have a slightly wrong bend somewhere? or the heat shield is hitting somewhere or is it the weak factory motor mounts and when i mash down on the throttle its flexing the exhaust into the underbody somewhere??? of coarse its something you cant just rev in the driveway in park. its only under a load it does it...

its not a everytime thing either but its frequent when im not driving "old manish" haha

also should i of just went with a 3 inch system and can i get a 3 inch now that the resonator is gone?

 

If you get it on a lift, or jack stands and use a creeper you should be able to see where it's hitting. (bare metal polished looking areas would be what you look for) Motor mounts are probably involved as they are soft... A 3" is going to do the same thing or worse if the 2 1/2 is hitting and you use it as a template, right?

 

I'm running three inch with no rubbing. When you get on it the motor flexes a bit, and greybeard is right there is contact somewhere. You can quick fix with some heat wrap, or have it rewelded

 

If you put a 3" system on your HHR, you will lose a lot more power, in your driveable power range, than you might gain on the higher end

 

Please find a hobby....giving out false info isn't needed here

 

I'm not here to argue. Nothing is ever 100% accurate all the time, but I was just talking from experience on over 25 years of doing exhausts

 

Hey Onelife1983,

Got your PM. Here is a video of the HAHN 3" with Cat-less DP. I rev'd and held to 4K(that would translate to about 90-95mph in final drive on the interstate, to give you an idea of engine "drone"). I used a Canon60D, so the sound is pretty accurate.

The slight smoke/condensation is normal since I no longer have cats. (I hope,...., it's not rings starting to go, that would suck). This is the first time I noticed this, it is pretty wet outside today, and it rained all yesterday, hope I'm just being paranoid.

http://youtu.be/TFBMqJSBVeU

From my experience with 3" exhaust, the car didn't notice it until I changed out the DP, then it was a whole new experience

 

Cute dog foolmoon. Now about that "mod" on the dog's tail.

 

$1,000 exhaust upstaged by a pom-pom thats all my fault... she got into a tick nest two weeks ago. I wouldn't make a good groomer

 

My point is each car is different

Fact is fuel is weak point on our cars at top end not flow

Example. I have auto and on dyno I showed better powerband with a cat
A friend has a manual and he benefitted from no cat

Both of us use 3" exhaust but gearing makes each of our powerbands different specially top end