I gave up trying for a baseline time of my stock HHR, and finally put in the IMCO muffler (already have the CGS on). But natually I had to be different. I put a Y pipe before the muffler, and ran it to a header collector, creating a true 'lake pipe'. By putting a solid plate between the collector and the exhaust tip, all the exhaust goes through the muffler. Remove the plate and I have open exhaust. Add a plate with a few holes in it, and I have a semi-open system. Here are some pic's.

 

Great set of picture! I'd like to know how that sounds!

 

I dont know yet. From the car it is not very loud totally open. But, I thought that the IMCO was too quiet. I have to get my son to video my driving around the block, then I will post it.

 

I'm kinda simple so let me break this down to see if I understand.

• full plate-single exhuast
• open plate-dual exhuast
• holes in plate-dual but with more to muffler

Is that it?

Are there any concerns about heat from the pipe routed to the passenger side?

 

Thats the story. The way the y pipe is, it only relieves the back pressure going into the muffler. It is actually a t, not a y. So not a lot of heat goes to the second pipe. But, it about a foot from the fuel emissons box behind the rear, and several inches below the spare tire well so I do not think that heat will be any problem. If so, I can always add a shield. But exhaust pipes run under the car without any heat issues.

 

I'm just thinking about my next mod.

Since we put the lakes on Bonnie's, I'm thinking of hiding her tailpipe so its not so obvious that the lakes are fake (I know they will all be capped, but most people may not even notice). so I'm thinking of a way of using her factory tip on my to give the appearance of dual exhaust. Would be even cooler if it really was!

What about back pressure? I thought that the HHR needed enough to run well. Wouldn't opening it lessen that and mean less performance? (I'm not bashing, just asking cause I don't know.)

 

That is an excellent question. I will have to test it both ways at the track to see (or with my GTech). But I am sure that the IMCO is not at the exact correct back pressure, so there will be some variance. And by using the right amount of holes in the blocking plate, if I could get it on a dyno, I would be able to find the sweet spot.

For now, it just sounds more aggressive. Plus, it has dual exhausts that are not phoney like the fake tail pipe someone sells on the internet. If anyone looks under the car, they will see it is connected!

 

I'm really loving what you've done and I'm thinking that this may be the way to go.

Keep the info coming, thanks.

 

Excellent work Lee!
You seem to know what it will take to get the best performance out of that system with the variable plate aperturs. Do you have a lift or are you jacking and grunting everytime you go beneath the HHR?

 

Looks good Lee Keep us posted on how it all works out